There are some people--and I am one of them--who think that the most practical and important thing about a man is still his view of the universe. We think that for a landlady considering a lodger it is important to know his income, but still more important to know his philosophy. We think that for a general about to fight an enemy it is important to know the enemy's numbers, but still more important to know the enemy's philosophy. We think the question is not whether the theory of the cosmos affects matters, but whether in the long run anything else affects them.
- Gilbert K. Chesterton, Heretics (1905)
The only critique of a philosophy that is possible and that proves something, ... [is] trying to see whether one can live in accordance with it ...
- Friedrich Nietzsche, Untimely Meditations (1873-1876)