Irons rusts from disuse, stagnant water loses its purity and in cold weather becomes frozen; even so does inaction sap the vigor of the mind. – Leonardo da Vinci, Notebooks, 1508

Belief is when someone else does the thinking. – Buckminster Fuller, 1972

A sect or party is an elegant incognito devised to save a man from the vexation of thinking. – Ralph Waldo Emerson

…the thoughtful excitement of lonely rambles, of gardening, and of other like occupations, where the mind has leisure to must during the healthful activity of the body, with the fresh and wakeful breezes blowing round it… – Augustus William Hare and Julius Charles Hare, Guesses at Truth, by Two Brothers