De partibus animalium

Of Nature's compositions, some things are ungenerated, imperishable and eternal, whereas others are generated and decay. The former are incomparably divine, but less accessible to knowledge. The evidence that might throw light on them, and on the problems that we long to solve concerning them, is provided only scantily by perception; by contrast, we have abundant information about perishable plants and animals, living as we do in their midst, and ample data may be collected about all their various kinds, if we are only willing to make sufficient effort. Both departments have their special charm. The imperfect concepts that we can form about things of essence give us, from their excellence, more pleasure than all our knowledge of the world in which we live, just as a glimpse of someone we love is more delightful than a leisurely view of other things, no matter how numerous or large. On the other hand, our knowledge of terrestrial things has the advantage in certainty and completeness. Moreover, their greater nearness and affinity to us balances somewhat the loftier interest of the essential things that are the subject of higher philosophy. Having already considered such essential things (as far as our conjectures could reach) we now proceed to treat of animals without omitting, to the best of our ability, any member of the animal kingdom, however ignoble. Although some animals do not charm our senses, even they can give great pleasure to all who are inclined to thinking and tracing the links of causality, for they may reveal to intellectual perception the artistic spirit that designed them...

...Therefore, we must not recoil with childish aversion from the examination of the humbler animals. Every realm of Nature is wondrous...

We should embark on the study of every kind of animal without disgust; for each and every animal will reveal to us something natural and beautiful. Nature's works exhibit in the highest degree a lack of randomness, and an ordering of everything towards goals; and the result of her generations and combinations is a beautiful form. If anyone thinks the investigation of the rest of the animal kingdom an unworthy task, he must consider the study of humans with similar disdain. For no one can look at the elements of the human body -- blood, flesh, bones, vessels and the like -- without much disgust.

When a part or structure is being studied, it should not be assumed that we are concerned with its material composition; that is not the subject of our study, but rather the relation of each part to the total form. Just as architecture is concerned not with building materials, but rather the form of buildings, so also the principal interest of natural philosophy is not material objects, but how they are put together and the totality of their form, independently of which they have no existence.