Few minds wear out; more rust out. – Christian N. Bovee

A just thinker will allow full swing to his scepticism. I dip my pen in the blackest ink, because I am not afraid of falling into my inkpot…. We are of different opinions at different hours, but we always may be said to be at heart on the side of truth. – Ralph Waldo Emerson, “Worship,” The Conduct of Life, 1860

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