Time not the Measure of Motion One thing seems strange to me, that whilst all men manifestly measured time by the motion of the great and visible bodies of the world, time yet should be defined to be the 'measure of motion': whereas it is obvious to every one who reflects ever so little on it, that to measure motion, space is as necessary to be considered as time; and those who look a little farther will find also the bulk of the thing moved necessary to be taken into the computation, by any one who will estimate or measure motion so as to judge right of it.