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

Stones grow, plants grow, and live, animals grow live and feel.

Blessed be the Lord for the beauty of summer and spring, for the air, the water, the verdure, and the song of birds.

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.

Nomenclature, the other foundation of botany, should provide the names as soon as the classification is made... If the names are unknown knowledge of the things also perishes... For a single genus, a single name.

We admit as many genera as there are different groups of natural species of which the fructification has the same structure.

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