What is left over if I subtract the fact that my arms goes up from the fact that I raise my arm?

Logic must look after itself. In a certain sense, we cannot make mistakes in logic.

What can be shown, cannot be said.

Every sign by itself seems dead. What gives it life?--In use it is alive. Is life breathed into it there?--Or is the use its life?

Philosophers are often like little children, who first scribble random lines on a piece of paper with their pencils, and now ask an adult 'What is that?

If you tried to doubt everything you would not get as far as doubting anything. The game of doubting itself presupposes certainty.

How small a thought it takes to fill a life.