That time, therefore, is the number of motion according to prior and posterior, and that it is continued, for it is of the continuous, is evident. The least number, however, simply considered, is the duad; but a certain number is partly the least, and partly not; as for instance, of a line the least number is in multitude two, or one; but there is not a least in magnitude; for every line is always divisible. Hence also similarly time; for one or two is the least according to number; but is not according to magnitude. It is also evident why time is not said to be swift and slow; but much and few, and long and short: for so far as it is continued it is long and short; but so far as it is number, it is much and few. It is not, however, swift and slow; for neither is any number with which we numerate swift and slow. The same time also is every where at once; but prior and posterior are not the same; because with respect to mutation, the present indeed is one, but the past and future are different. But time is number, not that with which we numerate, but that which is numbered. And this happens according to prior arid posterior to be always different; for the instants are different. The number is also one and the same of a hundred horses, and a hundred men; but the things to which the number belongs are different, viz. the horses and the men. Further still, as it happens that motion is one and the same, again and again, so also it happens with respect to time: as for instance, the year, the spring, or the autumns. We not only, however, measure motion by time, but time by motion, because they are bounded by each other: for time bounds motion, since itis the number of it; and motion bounds time. And we say, that time is much or few, measuring it by motion, in the same manner as we measure number by that which is numerable; as for instance, by one horse the number of horses: for by number we know the multitude of the horses; and again, by one horse we know the number of the horses. The like also happens in time and motion; for by time we measure motion, and by motion time. And this happens reasonably; for motion is consequent to magnitude, and time to motion; because these are quantities, and are continuous, and divisible: for because the magnitude is such, the motion suffers these things; and time, because of the motion. And we measure magnitude by motion, and motion by magnitude: for we say that the way is long, if the journey is long; and that this is long, if the way is long. We also say that the time is long, if the motion is much; and that the motion is much, if the time is long.
