Or we may look at it in another way. Suppose the earth were to turn twice as fast about itself and about the sun, the persons who lived sixty of such years would only have lived thirty of our present years, but they would have seen sixty revolutions of the earth, and, rigorously speaking, would have lived sixty years. If the earth turned ten times as fast, sixty years would be reduced to ten, but they would still be sixty of those years. We should live just as long; there would be four seasons, 365 days, &c., only everything would be more rapid: but it would be exactly the same thing for us, and the other apparently celestial motions having a similar diminution, there would be no change perceived by us. Again, consider the minute animals that are observable under the microscope, which live but for five minutes. During that period, they have time to be born and to grow. From embryos they become adult, marry, so to speak, and have a numerous progeny, which they develop and send into the world. Afterwards they die, and all this in a few minutes. The impressions which, in spite of their minuteness, we are justified in presuming them to possess, though rapid and fleeting, may be as profound for them in proportion as ours are to us, and their measure of time would be very different from ours. All is relative. In absolute value, a life completed in a hundred years is not longer than one that is finished in five minutes. It is the same for space. The earth has a diameter of 8,000 miles, and we are five or six feet high. Now if, by any process, the earth should diminish till it became as small as a marble, and if the different elements of the world underwent a corresponding diminution, our mountains might become as small as grains of sand, the ocean might be but a drop, and we ourselves might be smaller than the microscopic animals adverted to above. But for all that nothing would have changed for us. We should still be our five or six feet high, and the earth would remain exactly the same number of our miles. A value then that can be decreased and diminished at pleasure without change is not a mathematical absolute value. In this sense then it may be said that neither time nor space have any real existence.