A philosopher who is not taking part in discussions is like a boxer who never goes into the ring.
Source: Conversation, 1930 (published in Personal Recollections, ch. 6, ed. by Rush Rhees, 1981)
-- Ludwig Wittgenstein, (Apr 26 1889-1951), Austrian-English philosopher; He was one of the most influential figures in British philosophy; produced two original and influential systems of philosophical thought.