I think that to Lord Kelvin is attributed the saying that the scientific attitude to a thing, if you can't do anything else with it, is to measure it. This is the attitude I propose to adopt towards Time. The situation is to some extent analogous to the situation with regard to electricity. Science is unable to say what electricity is, and so it almost denies the word any entrance into a treatise on the subject. It replaces it by the word charge, which is something that can be measured. It is important to avoid hypostatizing time into a thing-in-itself. Instead of trying to say what time is (e.g. Plato's description of it as “the moving image of eternity”) we try to find a way of measuring it.