It is the essence of certainty to be established only with reservations.

It is the mission of the twentieth century to elucidate the irrational.

All thought of something is at the same time self-consciousness [...] At the root of all our experiences and all our reflections, we find [...] a being which immediately recognises itself, [...] and which knows its own existence, not by observation and as a given fact, nor by inference from any idea of itself, but through direct contact with that existence. Self-consciousness is the very being of mind in action.

The perceived world is the always-presupposed foundation of all rationality, all value, and all existence.

The world is... the natural setting of, and field for, all my thoughts and all my explicit perceptions. Truth does not inhabit only the inner man, or more accurately, there is no inner man, man is in the world, and only in the world does he know himself.

We know not through our intellect but through our experience.

Visible and mobile, my body is a thing among things; it's caught in the fabric of the world, and its cohesion is that of a thing. But, because it moves itself and sees, it holds things in a circle around itself.