Now all science starts gaily from the inland source of I don't know. Gaily it says: I don't know, but I'm going to know. It's like a little river bubbling up cheerfully in the determination to dissolve the whole world in its waves. And science, like the little river, winds wanderingly out again into the final I don't know of the ocean.

Selected Critical Writings, The Proper Study (p. 154), Oxford University Press. 1998