Motion with respect to the universal ocean of aether eludes us. We say, "Let be the velocity of a body through the aether", and form the various electromagnetic equations in which is scattered liberally. Then we insert the observed values, and try to eliminate everything which is unknown except . The solution goes on famously; but just as we have got rid of all the other unknowns, behold! disappears as well, and we are left with the indisputable but irritating conclusion —
Arthur Eddington