The thinker makes a great mistake when he asks after cause and effect: they both together make up the indivisible phenomenon.
All practical men try to bring the world under their hands; all thinkers, under their heads. How far each succeeds, they may both see for themselves.
Shall we say that a man thinks only when he cannot think out that of which he is thinking?
What is invention or discovery? It is the conclusion of what we were looking for.
It is with history as with nature and with everything of any depth, it may be past, present, or future: the further we seriously pursue it, the more difficult are the problems that appear. The man who is not afraid of them, but attacks them bravely, has a feeling of higher culture and greater ease the further he progresses.