The problem with this world is that smart people are full of doubts, while fools are convinced.

——Bertrand Russell

An unreflective life is not worth living.

——Socrates

There are things that can be done in life, and there are also things that cannot be done. Therefore, we must be careful and cautious about things that are controllable, and stay optimistic about things that are uncontrollable.

——Epictetus

Life consists in movement.

——Aristotle

People are like hedgehogs in the cold winter. If they are too close, they will sting each other. If they are far apart, they will be cold.

——Schopenhauer

A more advanced philosopher is alone, not because he likes to be alone, but because he can't find similar people around him.

——Nietzsche

Speak clearly what can be said, and remain silent about what cannot be said.

——Wittgenstein

Only by looking backward can we understand life, but to live well we must look forward.

——Kierkegaard

Then there is no victory at all, holding on means everything.

——Rilke

Poetically inhabiting the earth.

——Heidegger

No one will always be with you, so when someone is leaving, you must learn to wave goodbye.

——Socrates

The truth may be on the side of a few.

——Plato

Happiness is placing the soul in its proper place.

——Epicurus

Man is the sum of all social relations.

——Karl Marx

Instead of decorating yourself with gorgeous appearance, it is better to arm yourself with knowledge.

——Karl Marx

Self-discipline is freedom.

——Kant

Man is born free, but he is always in chains.

——Rousseau

Hell is other people.

——Sartre

Dreams express subconscious desires and conflicts in disguised form.

——Freud