Russell's books should be bound in two colours, those dealing with mathematical logic in red - and all students of philosophy should read them; those dealing with ethics and politics in blue - and no one should be allowed to read them.

This procedure [selecting the simplest law], however, has no logical justification but only a psychological one.

When you are philosophizing you have to descend into primeval chaos and feel at home there.

If we were to imagine an orange on the blue side or green on the red side or violet on the yellow side, it would give us the same impression as a north wind coming from the southwest.

Resting on your laurels is as dangerous as resting when you are walking in the snow. You doze off and die in your sleep.

Nothing is more important for teaching us to understand the concepts we have than to construct fictitious ones.

Knowledge is in the end based on acknowledgement.