I made the journey to knowledge like dogs who go for walks with their masters, a hundred times forward and backward over the same territory; and when I arrived I was tired.

The construction of the universe is certainly very much easier to explain than is that of the plant.

If another Messiah was born he could hardly do so much good as the printing-press.

When a book and a head collide and a hollow sound is heard, must it always have come from the book?

As I take up my pen I feel myself so full, so equal to my subject, and see my book so clearly before me in embryo, I would almost like to try to say it all in a single word.

One's first step in wisdom is to question everything - and one's last is to come to terms with everything.

A good part of the fame of most celebrated men is due to the shortsightedness of their admirers