What is the basic, the essential, the crucial principle that differentiates freedom from slavery? It is the principle of voluntary action versus physical coercion or compulsion.

[What for] was the first question he asked about any activity proposed to him - and nothing would make him act, if he found no valid answer. He flew through the days of his summer month like a rocket, but if one stopped him in mid-flight, he could always name the purpose of his every random moment. Two things were impossible to him: to stand still or to move aimlessly.

You have no choice about your capacity to feel that something is good for you or evil, but what you will consider good or evil, what will give you joy or pain, what you will love or hate, desire or fear, depends on your standard of value.

She thought: at this moment, the glass stem between his fingers feels just like the one between mine. We have this much in common.

No concept man forms is valid unless he integrates it without contradiction into the sum of his knowledge.

The uncontested absurdities of today are the accepted slogans of tomorrow.

The entire history of science is a progression of exploded fallacies.