Sitting on the moon?
In a recent blog post, Dennis des Chene replies to reflections by Mohan Matthen on the question whether some common sense intuitions may be resilient to refutation through science. In this context, Dennis comes up with an interesting thought experiment. Imagine a man sitting on the moon with his head pointing towards the Earth. For Dennis, the Aristotelian, it is clear that he is then “committed to holding that […] my feet are above my head (‘above’ being understood Aristotelian-wise); […]”. And this is meant to be true, because ‘up’ and ‘down’ are absolute notions (for an Aristotelian).
Graphics courtesy of Nadine Michael
Of course the idea that I’m sitting on the moon and have to assume that my feet are above my head seems to be pretty counterintuitive. But is it really? After all, we must take into account that sitting on the moon and facing the Earth is a fairly uncomfortable situation, at least for Aristotelians. Humans are made of two elements, earth and water. Both these elements tend to move towards the center of the universe. So it seems that the natural posture for Aristotelians on the moon is this:
We can see, everything is in order here: My feet are beneath my head, the moon is above it. The idea that my feet are above my head when sitting on the moon isn’t as far-fetched as it seems, as soon as it is clear that sitting on the moon is a posture against nature - as much as a headstand on Earth.
Now imagine that the Aristotelian on the moon looses his grip and falls towards Earth.. The following passage from the Physics gives us an idea of what should then happen:
ἔστι δὲ τὰ τοιαῦτα οὐ μόνον πρὸς ἡμᾶς, τὸ ἄνω καὶ κάτω καὶ δεξιὸν καὶ ἀριστερόν· ἡμῖν μὲν γὰρ οὐκ ἀεὶ τὸ αὐτό, ἀλλὰ κατὰ τὴν θέσιν, ὅπως ἂν στραφῶμεν, γίγνεται (διὸ καὶ ταὐτὸ πολλάκις δεξιὸν καὶ ἀριστερὸν καὶ ἄνω καὶ κάτω καὶ πρόσθεν καὶ ὄπισθεν), ἐν δὲ τῇ φύσει διώρισται χωρὶς ἕκαστον. (208b14-19)
Nor do such distinctions (up and down and right and left, &c.) hold only in relation to us. To us they are not always the same but change with the direction in which we are turned: that is why the same thing may be both right and left, up and down, before and behind. But in nature each is distinct, taken apart by itself.
For Aristotle, spatial terms express properties of substances rather than relations between substances, even though the common sense presumes the exact opposite. But this means that ‘natural place’ is determined not only with respect to ’ up’ and ‘down’, depending on the proportion of elements in the thing in place. Rather, substances have a natural ‘right’ and a natural ‘left’.
Johann Paschius defends this thesis in his 1685 dissertation “De loco”:
Paschius discusses two arguments for his view:
1. The argument from geographic orientation:
In II De Caelo, Aristotle teaches that movement of the spheres originates ‘on the right’ and all other cardinal points can be derived from that.
Idem alibi docet [sc. Aristoteles] dextrum id esse, unde principium motus est; hinc facile reliquas Loci differentias in Mundo à natura positas reperies, videlicet Ortus dextrum, Occasus sinistrum Septentrio faciem, Meridies dorsum, Zenith verticem, Nadir pedes cinget atque teget.
Moreover, in another text Aristotle teaches that the right is, whence the principle of motion comes from. Therefore, you will easily find the other differences of place as they have been posited by nature: the east encompasses and covers the right, the west the left, the north the front, the south the back, the zenith the top, the nadir the feet.
What Pasch seems to argue here is that there is a natural position in the world for human bodies: Facing north is more natural than facing south.
2. The argument from the spatial organisation of organisms:
[…] quod natura in ipsis animalibus hoc tam accurate observet, ut partibus singulis certum assignet locum et situm, huic dextrum, illi sinistrum, isti superiorem, alteri inferiorem; hanc retrò, aliam anté collocet. Si autem in quibusdam individuis earundem transpositio eveniat, illa pro monstris habentur.
[…] nature takes this [observer-independence of spatial properties] into account very accurately, as far as animals are concerned: She assigns a place and position to bodily parts, for this [sc. part] the right, for another the left, for this one a superior (sc. position), for another an inferior one. One part is placed at the back, another one in front. If in some individuals parts are transposed, such individuals are taken to be monsters.
The intuition behind the idea that there is a natural right-hand side of an organism is not as far-fetched as it seems at first glance. Imagine a teacher in front of his class, asking them to rise the left hand. This will always mean the left hand from the pupil’s point of view.
What does all this mean as far as the Aristotelian hanging from the moon is concerned? Imagine that he falls towards the earth. Aristotle’s theory of natural place (and natural non-relational local properties) suggests that it is more natural to land on one’s feet than on one’s head. Additionally, we should expect that our nose points towards the north, whereas our back-side points southwards.
But this landing position cannot be explained, or so it seems to me, by natural forces. The mixture of elements in a human body only explains the plain fact that it tends to fall towards the center of the earth. But how do we account for the fact that the spatial orientation of the body in falling (and landing) seems to be predetermined as well?
William Harvey’s Medical Aristotelianism – part III
Guest post by Benny Goldberg from the Department for History and Philosophy of Science, Pittsburgh
The previous blog post of this series discussed Harvey’s conception of anatomical experience. Now I turn to elements in Harvey’s view of experience that can be traced back to Galen.
Both Aristotle and Galen emphasize that, in order to achieve knowledge, one must make sure one is working with right sort of premises. And, for both, experience is the source of these premises. Anatomy, then, is the way in which one makes sure that the concepts in your premises are adequate to the phenomena: it is a process of definition, remembering that definitions for Galen and for Aristotle are accounts of the essences of those things (and, further, for both these authors and for Harvey, these essences are ultimately teleological, that is, they reveal what the thing being defined does). Here I will discuss the Galenic side of things, and in the next post I will discuss Harvey’s Aristotelian heritage.
Key, I think, to understanding the Galenic notion of experience are what he calls the ‘natural criteria’—these are the criteria by which we judge the similarity and differences in things such that we can define and understand them, or, to put it another way, to make sure our concepts are adequate to the natures of their subjects. We will return to the natural criteria in a moment, but let us first locate the origin of this idea in a particular text of Galen’s, namely his De placitis hippocratis et platonis, a work which I believe exerted a powerful influence over Harvey’s conception of experience and anatomy (here in the 1549 edition of the Opera Omnia) The De placitis was newly available to Western physicians in Humanist translations around the start of the sixteenth century, and was of fundamental importance in the renewal of anatomical practices by Vesalius and others, and was a key methodological text for physicians in training. This text places fundamental importance on anatomy as the prime method for investigating the soul of animals. Galen was a serious student of Aristotle’s works, and, as Teun Tieleman has argued, part of Galen’s criticism of the Peripatetics was just that some of their views on the soul (their cardiocentrism) were refuted by means of their own doctrines and methodologies! (Teun Tieleman 1996, Galen and Chrysippus on the Soul, 5. See Galen, De placitis, Lib.I, Cap.8) We should note that, though we have very little evidence regarding them and their doctrines, Galen was highly influenced by contemporary schools of Peripatetics, even and especially on his methodological doctrines.)As Galen writes,
…when Aristotle and Praxagoras affirm, contrary to anatomical observation, that the heart is the source of the nerves, they deserve to be censured. One can learn from the treatises they left that they observed with precision many other anatomical matters; but when they wrote about the source of the nerves, either they were completely blind themselves or they were addressing a blind audience. (Galen, De placitis, Lib.I, Cap.6)
So, to Galen at least, what he proposed methodologically was in agreement with Aristotle, even though the in terms of specific doctrines, Galen disagrees with the Philosopher. For Galen, experience provides the source of the premises used in demonstrations. In De placitis Lib.II, Galen argues that the problem with many demonstrations (those of Chrysippus especially) is that they use the wrong kind of premises. As Galen argues, the premises that are needed in this case are scientific premises, that is, those premises that pertain to the subject under investigation itself, as a substance. In other words, what are needed are premises that pertain to the essence of the subject under investigation. Above we saw that this, indeed, was what anatomy revealed for Harvey: the uses and actions which we understood as giving the essence of the parts of the body under investigation. So, for both Galen and Harvey, experience is the source of these premises. Galen in Lib.II goes over 4 sorts of experience, which are the following
What is evident to the mind
As Tielman has noted, Galen argues that to understand the parts of animals, simple sense perception and everyday experience are of quite limited use, and what is evident to the mind cannot resolve the issue (Tielman’s discussion of these notions is really wonderful, and I recommend anyone who is interested in Galen to read his work.) What is needed is technical experience, that is, experience gained through the art (techne) of anatomy.
Let us now return to the natural criteria. Galen describes the natural criteria in the following way:
Eyes in their natural state seeing what is visible; ears in their natural state hearing what is audible; the tongue sensing savors, the nostrils odors, the whole skin objects of touch; and besides, thought or mind or whatever you wish to call it, by which we distinguish entailment and incompatibility and other things that pertain to them, such as division and collection, similarity and dissimilarity…. (Galen, De placitis Lib.IX, Cap. 1 )
In De methodis medendi, Galen notes that the Ancients recognized two classes of evident things: those evident to the senses, hot, cold, pale, dark, etc, and those evident to the intellect, equality, similarity, causes, etc. But what is key to note here is that the senses and the mind are not strictly separated here in Galen, and thus experience and reason go hand in hand: in order to, as Galen notes, ‘distinguish entailment and incompatibility’ one must use the mind, reason. Sensation and intellection are the very criteria by which we can achieve scientific knowledge. One without the other can result only in Sophistry.
In just the same way, Harvey seems to endorse a picture of anatomy that unifies reason and experience as part of one and the same process. The art of anatomy is one of hand and mind, and, further, one that takes a lot of training and experiencing in order to perfect: it is a facultas a skilled ability to cut and see and understand the parts of animals. (Anyone who has performed a dissection can tell you that the insides of people look nothing like the neatly labeled diagrams in anatomy textbooks!)
I want to end this post by connecting up this last point, about experience, reason and similarities and differences to something that might otherwise be mysterious in Harvey: his regula Socratis, his invocation to use the ‘rule of Socrates.’ This is a phrase that, so far as I can tell, does not appear in any other work by Harvey or anyone else. Harvey only uses the phrase twice in his Prelectiones, but, despite this, the rule of Socrates is central to his methodology over the course of his whole career.
The phrase occurs in Harvey’s ‘Canones anatomae generalis,’ which are a set of suggestions and heuristics for the proper performance of an anatomy. In his fifth canon anatomae generalis, Harvey exhorts students:
To review one’s own and another’s observations to confirm your own opinion, or in the strictest form, deal with other animals according to the rule of Socrates: where it is farer written. Whence exotic observations:
about the causes of disease: chiefly useful to the physician
about the variety of Nature: [chiefly useful] to the philosopher
for the purpose of refuting errors and solving problems
for the purpose of discovering uses and actions, excellences, and thus also on account of these, their classifications
The end of an anatomy is knowledge of a part, its purpose, its necessity and use. Its [anatomy’s] chief purpose for Philosophers is to learn which [parts] are required for each action insofar as it is excellent. Likewise [its chief purpose] for Physicians is [to learn] the natural constitution [of the parts], [that is] the standard by which they must classify those who are sick, and then what they must do in diseases.
So, the Rule of Socrates is Harvey’s way of talking about his use of comparative anatomy, and he thinks it necessary in order to understand the purpose and essence of the parts. This is perhaps the most innovative aspect of Harvey’s method, and it is one that, though we find it in other authors including Aristotle, is stressed more by Harvey than by almost anyone else—indeed, it is one of the primary ways Harvey takes other anatomists to task in his De motu cordis, claiming that their looking only at humans (and dead ones at that) is what led them astray in their understanding of the heart and the blood.
If we look at the other occurrence of the regula Socratis, we can connect this method of Harvey’s to Galen’s conception of the natural critieria and the importance of distinguishing similarity and difference:
[Called ‘caecum’] since its office is obscure. The size of a worm. In man, it is [counted] among the great [guts] for the sake of classification, as with the nipples. Conversely [in] hoggs, hare[s], oxen, ratt[s], etc., it is almost like another belly [in size]. In man it is sometimes large, as in the foetus WH, [as] Salomon Albertus [says], it is sometimes entirely absent. Thus the rule of Socrates through similarity in a great print.
Quia caecum officio. Magnitudo vermis. Homine inter magna tamen notae gratia ut paipillae. Contra hoggs, hare, oxen, ratt, etc., tanquam alter ventriculus. Homini aliquando magnum, ut foetu WH, Sal. Albert, aliquando non omnino. Hinc Socratis regula per similitudinem in a great print (Harvey 1616-1627 f.20.)
What the rule of Socrates allows is to be able to compare across animals and to discover the purposes of things which would otherwise be obscure. The reference to ‘similarity in a great print’ is a reference to Plato’s Republic, where he argues we can look at the city to understand the soul, as it’s easier to observe and understand. In the same way, Harvey, following Galen, thinks that by looking across animals, by obeying the rule of Socrates, we can compare and contrast and thus distinguish the similarities and differences in things which would otherwise be obscure in the case of a single specific animal. We can often see things more easily in comparative perspective, because the same organ might be larger, or easier to dissect, that is, it might be set up ‘in a great print’ and hence it will be easier to read off the uses and actions and determine the essence of this thing
Why is this called the rule of Socrates? The answer, I think, lies in a passage from Aristotle. If we think about Socrates’ method, we realize that it involves interrogating others so as to be able to find the truth of available opinions. This is what Harvey suggests: It is a method of interrogating one’s own opinions about the parts by, not only as Socrates does, by investigating other people’s opinions, but also by looking directly at the parts of different animals. And, as Aristotle wrote in the Metaphysics:
δύο γάρ ἐστιν ἅ τις ἂν ἀποδοίη Σωκράτει δικαίως, τούς τ᾽ ἐπακτικοὺς λόγους καὶ τὸ ὁρίζεσθαι καθόλου: ταῦτα γάρ ἐστιν ἄμφω περὶ ἀρχὴν ἐπιστήμης ( via Perseus )
…for two things may be fairly ascribed to Socrates: inductive arguments and universal definition, both of which are concerned with the starting-point of science…. (Metaphysics XIII. 4)
Definition and induction are just those things we have been discussing: using many experiences (induction) to determine the essences of the parts (definition).
William Harvey’s Medical Aristotelianism Part II
Guest post by Benny Goldberg from the Department for History and Philosophy of Science, Pittsburgh
In this post, I will continue with some themes which I broached in my previous blog post. Specifically I will talk about Harvey’s conception of experience.
In my last post I described Harvey’s philosophy as ‘medical Aristotelianism’. One might have called this ‘Galenic Aristotelianism,’ because, for Harvey and for every other physician operating in Europe at this time, Galen is a looming presence in the background. In a certain sense, much of Harvey’s Galenism is hard to detect, for Harvey rarely quotes from or references Galen (especially in comparison with Aristotle), and when he does do so, it is usually in matters of fact and not method or theory. But, especially in his notes for the Lumleian lectures, the Prelectiones anatomie universalis (written and revised from 1616-1627), Galen influence on Harvey is quite apparent once one knows what to look for (though it may be tempting to overstate this, and so one should take what I write here as preliminary and tentative).
In this post, then, I want to explore the ways in which Harvey’s conception of experience is indebted to Galen. (In a subsequent post I will discuss the more Aristotelian side of Harvey’s thought.) And though Harvey’s contemporaries and their methods and traditions are important, I shall, as Harvey himself recommended to Aubrey, return to this particular ‘fountain head’ and ignore the ‘shitt-breeches’
The category of ‘experience’ in natural philosophy is a convoluted and complicated one in the early modern period, and is furthermore undergoing a tremendous shift. The Aristotelians had long maintained that ‘there is nothing in the intellect not previously in the senses’, but what this phrase means is different in different authors. As Stefan Heßbrüggen explores in his draft paper, the role that the senses play in producing concepts and justifying assertions is quite variable even amongst the Aristotelians! Terminologically, the Latin ‘experientia’ and ‘experimentum’ are used interchangeably by most authors, and both mean ‘experience’—I am unsure when the modern sense of ‘experiment’ comes to be clearly distinguished, but it is not in the first half of the seventeenth century! (Many have maintained otherwise, but I am unconvinced; a future project of mine involves using quantitative methods to see if we can track shifts in meaning of these terms).
Experience and experiment for Harvey indicate observation, and though some of what he does in the De motu cordis seems to us to be modern experiments, Harvey himself does not distinguish, say, the ligature procedures he uses to trace the blood flow from the observations he makes from dissecting animals. So what role do these experientiae play in Harvey’s work?
Harvey, unfortunately, never says exactly what he means by experience, what role it plays in his natural philosophy, and so, to understand him, we must scour his works to see if we can put together a picture of what is going on. Key here is the earliest work we have from him, his Prelectiones, which I shall concentrate on in this post. It will be helpful to describe this work, as it has been almost entirely ignored by Harvey scholars, even though it is a veritable treasure trove of information. (I had the pleasure of spending a summer studying the original manuscript in 2009 at the British Library thanks to a grant from the Wesley Salmon Fund at the University of Pittsburgh.)
The ability to dissect human bodies was ensured by Queen Elizabeth I in 1565, who gave the College of Physicians the right to dissect annually the bodies of up to four criminals hanged in London, in Middlesex or in any county within a radius of 16 miles. From roughly this point on, the College appointed one of their fellows to give a public lecture on an anatomy. These were called the Lumleian lectures, which were founded by John Lumley in 1582, having been given the seal by Queen Elizabeth.
The duty of the lecturer was to provide, over the course of 6 years, a twice weekly lecture, in both Latin and English, concerning the ‘whole art of surgerie.’ Though the tripartite indenture between Lord Lumley, Richard Caldwell and the President of the Royal College of Physicians establishing the lecture designates a particular course of study, down to the recommended textbooks, Harvey ignored this, and, instead, bases his lectures on his own research, the Theatrum Anatomicum of Bauhin, and the Historia Anatomica of Laurentius.
Harvey was appointed Lumleian lecturer in August 1615 and in the following spring conducted his first public anatomy; he was the fourth such Lecturer. Harvey’s notes seem intended to be given during an actual dissection, as opposed to a mere lecture on anatomy from various authoritative texts, though there is an element of this in the notes. Harvey gave these lectures every two years and added to his notes until at least 1627.
The notes are just that: notes. They are organized, in some places quite complexly, but they are also written over, marked on, with parts crossed out, lines drawn to place added bits, and various notes written in the margins. The order of parts of the text is also somewhat puzzling: for instance, why do the Canones Anatomiae generalis (Harvey 1616, Prelectiones anatomie universalis, f.4.) come immediately after the session on division (loc. cit., f. 1-3), and before the section titled In historia anatomica (loc cit., f.5) Indeed, on some pages there are even doodles, meant to remind Harvey to use his hand to show the numbering of his points to help the students keep track of them. They are, to say the least, messy: Harvey’s handwriting is notoriously terrible—even with the low standards set for the writing of physicians—and his Latin is often mixed with bits of English. His sentences are often no such thing, mere fragments, phrases, or words. In my research, I found a number of mistakes and errors in transcriptions of the original. In addition, the existing translations are all very problematic (All the problems stem from Harvey’s handwriting, which in some parts we must speculate entirely as his scrawl is entirely illegible), and thus I have tried to provide my own translations and the original Latin text in order to make apparent all the choices and inferences made in translating Harvey’s notes into understandable English.
Finally, the following picture is a sample of the text, just to give you an impression of their state and appearance.
Returning now to our theme, to understand Harvey’s conception of experience we must understand it as anatomical experience. Experience for Harvey is, and this is central, skilled experiencing. Experiencing in an anatomy is a matter of ability and learning, it is trained.
We will start, then, with Harvey’s definition of anatomy, the very first line of his Prelectiones (though an inspection of the manuscript reveals that this line was added later). We will look at the line in Latin before providing the translation:
Anatomia est facultas quae occulari inspectione et sectione partium usus et actiones (Harvey 1616, f.1.).
This is a difficult line to translate, because Harvey’s Latin here is so sparse, and certain key verbs are missing. So, for instance, the relationship between ocular inspection and cutting and their uses and actions is unclear. Another difficulty is how to render ‘facultas’; Whitteridge translates it as ‘branch of learning’ but this is a much too modern conception of anatomy. Instead, we must translate the line like this:
Anatomy is an ability which [teaches us] the uses and actions of the parts through ocular inspection and cutting.
Facultas is a word which denotes an ability, in particular, an ability to do something well. So, for instance, in a dictionary of Latin to English from the 1640s, Francis Holy-oke’s (1640) Dictionarium Etymologicum Latinum the definition of a facultas is “Power to doe or speak, leave, licence, feaxe, promptnesse, eloquence.” Anatomy, then, is an ability to do something (and do it well), it is the result of training and practical experience.
Anatomical experience, then, is active: if we turn again to that dictionary, we see that the word anatomia generally denoted a specific instance of performing a dissection: “An Anatomie or cutting up of the body to see the parts.” This is in line with the etymology of the word, which stems from the Greek word for ‘dissection’, from ana- ‘up’ and temnein ‘to cut,’ and, indeed, Holy-oke provides the Greek in the entry. Note first that the goal of anatomy—to see the parts—is mentioned in this very brief definition. The emphasis here is clearly on the activity of dissection, or as an early modern Englishman might say it, ‘anatomizing.’ In other words, the term ‘anatomy’ here emphasizes the process of cutting up a body on a particular occasion more so than it does the product of such cutting (seeing the parts). Indeed, when one considers the wider cultural context of anatomical practices in early modern Europe, this conception of anatomy as an event should come as no surprise. Anatomy was viewed as a public spectacle, a social occasion, and anatomy theaters were built for viewing such civic events. Returning to Harvey’s own definition, at the beginning of the Prelectiones, we find that he, too, emphasizes the active nature of anatomy by emphasizing that it is an ability to do something.
For Harvey anatomy is the ability to learn the ‘uses and actions’ of the parts. This terminology, though Galenic in origin, is a feature shared by both Aristotle and Galen. The uses and actions of the parts are the final causes and efficient causes of a part: so, the use of the heart is to push the blood around the body and the action of the heart is its pattern of systole and diastole by which it effects the circulation. (Though some have argued that Harvey does not speak of final causes this is incorrect, for he does provide the final cause of the heart in the De motu, which just is the circulation; what he cannot figure out, however, is the use of the circulation, which is a separate matter from the use of the heart.) If we remember the doctrines of the De anima, then, we realize that what we learn about through anatomy is the soul of the creature under investigation: we learn about soul in all three senses that Aristotle notes: as the efficient cause (actions) and as the formal and final cause (uses, remembering that, in natural things, the formal and final causes are identical). In other words, what we learn by doing anatomy is the very essence of the parts of the body, their formal natures.
Anatomical experience, then, is used to learn the essences, the uses and actions of the parts. Although Andrew Wear’s (1983) “Harvey and the Way of the Anatomists” emphasizes Harvey’s indebtedness to the anatomical tradition by arguing that Harvey endorses a view in which ‘observational knowledge’ is worthwhile in its own right, we see that, in the Prelectiones at least (and I would maintain throughout his work though I won’t argue for it here) Harvey understands the goal of anatomy as a distinctly causal one. This is in keeping with his Galenic and Aristotelian knowledge, and, indeed, with the larger early modern understanding of science.
Wear tries to argue (and in this many including Roger French have followed) that Harvey accepts the traditional distinction in anatomy between the art of anatomy (the ability to cut up bodies) and the knowledge of anatomy (the science of the body and its causes). The former produces no knowledge and is historical, which is to say, observational; the latter is scientific, and stems from book learning. This conception of anatomy, found in many authors from Laurentius in his (1600) Historia anatomica to Glisson in his (1645) Anatomia hepatis, distinguishes between the art of anatomy, which is experiential, and the science of anatomy, which is rational. So, according to Wear, what we have in Harvey is an attempt to say that the experiential counts as knowledge.
This, I think, fundamentally misunderstands Harvey. Indeed, by locating Harvey’s ‘observational knowledge’ in the tradition of the anatomists, I think it misunderstands a great deal, for the anatomists, more so perhaps than other philosophers, often emphasized the ways in which experience and reason must be combined to produce knowledge. And in Harvey we find that his definition of anatomy is perhaps even more unified than those of other anatomists. Harvey understands that both experience and reason are part of one and the same process; so, in the De generatione, Harvey writes about the theories of previous philosophers on generation, and argues that the fact that,
…these are false and rash sayings will be established easily, and having employed the light of anatomy they will suddenly vanish just like phantoms of the night; nor will they need a laborious refutation, when through ocular inspection you yourself, Reader, shall discover the contrary and find it conformable to reason, having been made more certain by your own eyes; and at the same time, you will understand how unsafe, no, how truly base, it is to be taught from the commentaries of others without a test of the things themselves; especially since the book of Nature is so open and accessible.
Verum haec falsa, & temere dicta esse, facile constabit; & veluti tenebrarum phantasmata (adhibita luce anatomica) subito evanescent, nec redargutionem operosam requirent, ubi per autopsiam contraria, eaq; rationi consentanea, ipsemet (Lector!) propriis oculis certior factus, deprehenderis; simulque intellexeris, quam sit intutum, imo vero turpe, citra rerum ipsarum examen, ex aliorum commentariis institui; praesertim, cum tam apertus facilisque Naturae liber sit.
(Harvey, William (1651), “Praefatio,” In: De generatione animalium, London: B1)
Harvey here does not dismiss book learning nor reason: rather he emphasizes how they must come together with experience in order to be tested. Autopsia—seeing for oneself— is central to Harvey’s conception of anatomical experience, but not as a replacement for reason, but as a way to ensure that one’s concepts of things in the world are true and accurate, to ensure that one is finding the true nature and essence of whatever one is investigating. Reason and experience are a package deal, and you’d be crazy not to take up what it offers.