There are three principal means of acquiring knowledge... observation of nature, reflection, and experimentation. Observation collects facts reflection combines them experimentation verifies the result of that combination.

• When superstition is allowed to perform the task of old age in dulling the human temperament, we can say goodbye to all excellence in poetry, in painting, and in music.
• Genius is present in every age, but the men carrying it within them remain benumbed unless extraordinary events occur to heat up and melt the mass so that it flows forth.
• When science, art, literature, and philosophy are simply the manifestation of personality they are on a level where glorious and dazzling achievements are possible, which can make a man's name live for thousands of years.
• The best doctor is the one you run to and can't find.
• There are things I can't force. I must adjust. There are times when the greatest change needed is a change of my viewpoint.
• People praise virtue, but they hate it, they run away from it. It freezes you to death, and in this world you've got to keep your feet warm.
• Although a man may wear fine clothing, if he lives peacefully and is good, self-possessed, has faith and is pure and if he does not hurt any living being, he is a holy man.
• The general interest of the masses might take the place of the insight of genius if it were allowed freedom of action.
• Man will never be free until the last king is strangled with the entrails of the last priest.
• Morals are in all countries the result of legislation and government they are not African or Asian or European: they are good or bad.