Before you begin, study unceasingly, but once started, make mistake if you must but you must execute freely (12 May 1855). - Eugène Delacroix

Beavers will invent a new way of building dams before architects accept a new method or a new style in their art (23 August 1854).

For a man who is sensitive to nature, happiness consists in expressing nature. How infinitely happy, then, is the man who reflects nature like a mirror without being aware of it, who does the thing for love of it and not from any pretensions to take first place. This noble unself-consciousness is what we find in all truly great men, in the founders of the arts. I picture the great Poussin, in his retreat, delighting in the study of the human heart.. ..I picture Raphael in the arms of his mistress, turning from La Fornarina to paint his Saint Cecilia.. ..I am only too well aware that I am far not only from their divine spirit, but even from their modest simplicity...

I saw a procession of ants moving along the path in a way which I challenge any naturalist to explain. The entire tribe seemed to be moving in formation as if they were emigrating, with a few worker-ants going along the column in the opposite direction. Where could they have been going?
We are all shut up together higgledy-piggledy, animals, men, and plants, in this vast box they call the universe. We claim to be able to read the stars and to make conjectures about the past and the future, which are both beyond the range of our vision, and yet we understand nothing of the things in front of our eyes. (Tuesday 30 April 1850).