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

There are as many species as the infinite being created diverse forms in the beginning, which, following the laws of generation, produced many others, but always similar to them: therefore there are as many species as we have different structures before us today.

It is the genus that gives the characters, and not the characters that make the genus.

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.

To live by medicine is to live horribly.

A herbarium is better than any illustration; every botanist should make one.

Nature does not proceed by leaps.