Leonardo da Vinci would walk across Milan to change a single tint or the slightest detail in his famous picture of the Last Supper. "Every line was then written twice over by Pope," said his publisher Dodsley, of manuscript brought to be copied. Gibbon wrote his memoir nine times, and the first chapters of his history eighteen times. 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. "I now see that you can use your eyes."
Reynolds said he could go on retouching a picture forever.
The captain of a Nantucket whaler told the man at the wheel to steer by the North Star, but was awakened towards morning by a request for another star to steer by, as they had "sailed by the other."
Stephen Girard was precision itself. He did not allow those in his employ to deviate in the slightest degree from his iron-clad orders. He believed that no great success is possible without the most rigid accuracy in everything. He did not vary from a promise in the slightest degree. People knew that his word was not "pretty good," but _absolutely_ good. He left nothing to chance. Every detail of business was calculated and planned to a nicety. He was as exact and precise even in the smallest trifles as Napoleon; yet his brother merchants attributed his superior success to good luck.