At the core of all well-founded belief lies belief that is unfounded.

If a person tells me he has been to the worst places I have no reason to judge him; but if he tells me it was his superior wisdom that enabled him to go there, then I know he is a fraud.

I am not interested in constructing a building, so much as in having a perspicuous view of the foundations of possible buildings.

Where two principles really do meet which cannot be reconciled with one another, then each man declares the other a fool and a heretic

To think that you are not following a rule is to follow a rule.

The sense of the world must lie outside the world... What we cannot speak about we must remain silent about... What can be described can happen too, and what is excluded by the laws of causality cannot be described.

Like everything metaphysical the harmony between thought and reality is to be found in the grammar of the language.