Physics most strongly insists that its methods do not penetrate behind the symbolism. - Arthur Eddington

We used to think that if we knew one, we knew two, because one and one are two. We are finding that we must learn a great deal more about ‘and.

Consciousness is not wholly, nor even primarily a device for receiving sense-impressions.

It is of interest to inquire what happens when the aviator's speed … approximates to the velocity of light. Lengths in the direction of flight become smaller and smaller, until for the speed of light they shrink to zero. The aviator and the objects accompanying him shrink to two dimensions. We are saved the difficulty of imagining how the processes of life can go on in two dimensions, because nothing goes on. Time is arrested altogether. This is the description according to the terrestrial observer. The aviator himself detects nothing unusual; he does not perceive that he has stopped moving. He is merely waiting for the next instant to come before making the next movement; and the mere fact that time is arrested means that he does not perceive that the next instant is a long time coming.