Once one knows what really matters, one ceases to be voluble. And what does really matter? That is easy: thinking and doing, doing and thinking - and these are the sum of all wisdom. . . . Both must move ever onward in life, to and fro, like breathing in and breathing out. Whoever makes it a rule to test action by thought, thought by action, cannot falter, and if he does, will soon find his way back to the right road.