Of one of his works Montesquieu said to a friend: "You will read it in a few hours, but I assure you it has cost me so much labor that it has whitened my hair." He had made it his study by day and his dream by night, the alpha and omega of his aims and objects.

"He who does not write as well as he can on every occasion," said George Ripley, "will soon form the habit of not writing well on any occasion." An accomplished entomologist thought he would perfect his knowledge by a few lessons under Professor Agassiz.

The latter handed him a dead fish and told him to use his eyes.

Two hours later he examined his new pupil, but soon remarked, "You haven't really looked at the fish yet.
You'll have to try again." After a second examination he shook his head, saying, "You do not show that you can use your eyes." This roused the pupil to earnest effort, and he became so interested in things he had never noticed before that he did not see Agassiz when he came for the third examination.

"That will do," said the great scientist.