I demand of you, and of the whole world, that you show me a generic character... by which to distinguish between Man and Ape. I myself most assuredly know of none.

The first step in wisdom is to know the things themselves; this notion consists in having a true idea of the objects; objects are distinguished and known by classifying them methodically and giving them appropriate names. Therefore, classification and name-giving will be the foundation of our science.

In natural science the principles of truth ought to be confirmed by observation.

To live by medicine is to live horribly.

There are some viviparous flies, which bring forth 2,000 young. These in a little time would fill the air, and like clouds intercept the rays of the sun, unless they were devoured by birds, spiders, and many other animals.

Yet man does recognise himself [as an animal]. But I ask you and the whole world for a generic differentia between man and ape which conforms to the principles of natural history, I certainly know of none... If I were to call man ape or vice versa, I should bring down all the theologians on my head. But perhaps I should still do it according to the rules of science.

There is no generation from an egg in the Mineral Kingdom. Hence no vascular circulation of the humours as in the remaining Natural Kingdoms.