LECTURE 18 (219 b 9-220 a 23)

HOW THE SAME 'NOW' IS OR IS NOT IN THE WHOLE OF TIME. THE MEANING OF THINGS WHICH ARE SAID OF THE 'NOW'

             582. After the Philosopher has shown what time is, he here treats the 'now'.

             First he shows whether there is the same 'now' or different 'nows' in the whole of time. This problem was mentioned above. Secondly, where he says, 'Clearly, too, if there were . . .' (219 b 34), he establishes from the above the meaning [ratio] of those things which are said of the now'.

             Concerning the first part he makes three points. First he states that the 'now' in a way is the same, and in a way it is not. Secondly, he explains this, where he says, 'The "now" in one sense . . .' (219 b 13). And thirdly he proves it, where he says, '. . . for motion, as was said . . .' (219 b 15).

             583. He says, therefore, first that since time is the number of motion, then just as the parts of motion are always different, so are the parts of time. But that which exists together with the whole of time, that is, the 'now', is the same. Insofar as it is, it is the same. But in reason [ratio] it is different insofar as it is before and after. And thus the 'now' measures time, not insofar as it is the same in subject, but rather insofar as in reason [ratio] it is different and before and after.

             584. Next where he says, 'The "now" in one sense . . .' (219 b 13), he explains this. He says that the 'now' in a way is always the same, and in a way it is not. For insofar as the 'now' is always considered as in another and another according to a succession of time and motion, it is different and is not the same. And this is what we meant when we said above that the 'now' is different. For the meaning [ratio] of 'now' is taken here as in the onrush of time and motion. But insofar as the 'now' is a certain being, it is the same in subject.

             585. Next where he says, '. . . for motion, as was said . . .' (219 b 15), he proves what he has said.

             First he proves that the 'now' is the same in subject but different in reason [ratio]. Secondly, where he says, 'This is what is . . .' (219 b 29), he proves that the 'now' measures time.

             He says, therefore, first that, as was said above, in respect to continuity and before and after, motion is consequent upon magnitude, and time is consequent upon motion. Let us imagine that in geometry a moved point produces a line. In a similar way the same thing must also be true of time, as it is also true of motion. Moreover, if the point by its own motion produces a line, then that very point which is moved is that by which we know the motion and the before and after in the motion. For motion is perceived only because the mobile object is different. That which pertains to a preceding disposition of the mobile object we judge to be prior in the motion, and that which pertains to a following disposition of the mobile object we judge to be posterior in the motion. That which is moved (by which we know motion and by which we discern the before and after in motion) is a point, or a stone, or something else. In regard to that by which it is a certain being, whatever it is, it is the same in subject, but it is different in reason [ratio]. However the sophists use the word 'different' in the following way when they say that there is a different Coriscus in the theatre and in the market-place. By a sophism of accident they argue as follows: being in the market-place is different than being in the theatre. But Coriscus is now in the market-place and later in the theatre. Therefore, he is other than himself. Hence it is clear that that which is moved, although it is the same in subject, is different in reason [ratio] in that it is now here and then there.

             But just as time is consequent upon motion, likewise the 'now' is consequent upon that which is moved. He proves this from the fact that we know the before and after in motion by means of the mobile object. For when we find a mobile object in some part of a magnitude through which it is moved, we judge that motion through one part of the magnitude happened first, and motion through another part of the magnitude follows later. And likewise in the numbering of motion by time, that which distinguishes the before and after of time is the 'now', which is the end of the past and the beginning of the future. Therefore, the 'now' is related to time as the mobile object is related to motion. Further, by rearranging the proportion, time is related to motion as the 'now' is related to the mobile object. Hence, if the mobile object is the same in subject in the whole motion but different in reason [ratio], likewise it will be necessary that the 'now' is the same in subject but different in reason [ratio]. For that by which the before and after are distinguished in motion (that is, the mobile object) is the same in subject but different in reason [ratio]. And that according to which the before and after in time are numbered is the 'now' itself.

             586. Moreover, from these considerations an understanding of eternity can be easily had. For the 'now', insofar as it corresponds to a mobile object differently related, distinguishes the before and after in time. And by its flux it produces time, as a point produces a line. Therefore, when different dispositions are removed from a mobile object, there remains a substance which is always the same. Hence the 'now' is understood as always stationary, and not as flowing or as having a before and after. Therefore, as the 'now' of time is understood as the number of a mobile object, the 'now' of eternity is understood as the number, or rather the unity, of a thing which is always the same.

             587. Next where he says, 'This is what is . . .' (219 b 29), he shows how the 'now' measures time.

             He says that that which is best known in time is the 'now'. And everything is measured by that which is best known in its genus, as is said in Metaphysics, X. He also shows this by means of the relation of motion to the mobile object. Motion is known by that which is moved, and local motion by that which is moved locally, as the less known is known by the more known. This is so because that which is moved is 'a this', that is, a certain thing stable in itself, which is not true of motion. Hence the mobile object is more knowable than motion; and motion is known by means of the mobile object. And likewise time is known by means of the 'now'. Thus he concludes to the main point: that which is called the 'now' in a way is always the same, and in a way is not. For it is similar to the mobile object, as was said.

             588. Next where he says, 'Clearly, too, if there were . . .' (219 b 34), he establishes the meaning [ratio] of those things which are said of the 'now'. First he establishes the meaning of the statement, 'there is no time except the "now" '. Secondly, where he says, 'Time, then, also is . . .' (220 a 5), he establishes the meaning of the statement, 'the "now" divides the parts of time and makes them continuous'. Thirdly, where he says, '. . . and further because . . .' (220 a 17), he establishes the meaning of the statement, 'the "now" is not a part of time'.

             589. He says, therefore, first that it is clear that, if there were no time, there would be no 'now', and if there were no 'now', there would be no time. This is so because of the relation of motion to the mobile object. For just as local motion and that which is moved are together, likewise the number of that which is moved and the number of local motion are together. But time is the number of local motion. Moreover, the 'now' is related to that which is moved not as a number (for the 'now' is indivisible), but as the unity in number. Therefore, it follows that time and the 'now' do not exist without each other. Moreover, it must be noted that time is always related to local motion, which is the first motion. For time is the number of the first motion, as was said.

             590. Next where he says, 'Time, then also is . . .' (220 a 5), he establishes the meaning [ratio] of the statement, 'time is made continuous and is divided by the "now" '. He does this first by means of motion and the mobile object, and secondly, where he says, 'Here, too, there is . . .' (220 a 9), by means of a line and a point.

             He says, therefore, first that it is now clear from the foregoing that time is a continuum because of the 'now', and time is divided by the 'now'. This follows from that which is found in local motion, whose number is time, and from that which is moved in respect to place, to which the 'now' corresponds. For it is clear that every motion has unity from that which is moved, because that which is moved remains one and the same in the whole motion. And when one motion continues, that which is moved is not just any being, but rather the same being which began to be moved in the first place. For if there were another being which was moved later, the first motion would have ended, and there would then be a motion of a different mobile object. Thus it is clear that the mobile object gives unity to motion, and this is its continuity.

             However it is true that the mobile object is different according to reason [ratio]. He distinguishes the before and after part of motion as follows. Insofar as motion is considered by one understanding [ratio] or disposition, one realizes that before this there was some other disposition of the mobile object which pertained to a prior part of the motion. Moreover, whatever comes after this will pertain to a later part of the motion. Therefore, the mobile object makes the motion continuous and divides it. And the 'now' is related to time in the same way.

             591. Next where he says, 'Here, too, there is . . .' (220 a 9), he establishes the same thing by means of a line and a point. He says that that which was said about time and the 'now' agrees in a certain way with what is found in a line and a point. For a point makes a line continuous, and divides it insofar as it is the beginning of one part and the end of another.

             Nevertheless, there is this difference between a line and a point, and time and the 'now'. A point and a line are at rest. Hence, one can take the same point twice and use it as two, that is, as a beginning and as an end. And when we so use a point as two, it remains at rest, as is clear in reflex motion in which the end of the first motion is the beginning of the second reflex motion. Because of this it is proven below in Book VIII that reflex motion is not continuous, but a state of rest intervenes.

             But the 'now' is not at rest, because it corresponds to the mobile object which is always in motion while the motion lasts. Because of this the 'now' is always different in respect to reason [ratio], as was said above. Therefore, although time is the number of motion, it does not number motion in that the same time is taken as the beginning of one part and the end of another. Rather time numbers motion when two extremities of time, that is, two 'nows' (which, nevertheless, are not parts of time), are taken.

             The reason why this kind of numbering pertains to time, rather than the other kind, in which the parts of a line are numbered by a point as a beginning and end, is as follows. When one uses a point twice, an intermediate state of rest results, and this cannot occur in time and in motion. Nevertheless, it must not be understood from what has been said that the same 'now' is not the beginning of the future and the end of the past. The point here is that we do not perceive time by numbering motion with one 'now', but rather by two 'nows', as was said. For otherwise it would follow that in numbering motion the same 'now' would be taken twice.

             592. Next where he says, '. . . and further because . . .' (220 a 17), he establishes the meaning [ratio] of the statement, 'the "now" is not a part of time'.

             He says that it is clear that the 'now' is not a part of time; just as that by which motion is distinguished, that is, a designated disposition in the mobile object, is not a part of motion. Nor are points parts of a line. Rather two lines are parts of one line.

             However, he explains the properties of time by means of motion and a line. For, as was said above, motion is continuous because of magnitude, and time is continuous because of motion.

             Finally he concludes that the 'now', insofar as it is a terminus, is not time, but is related to time as terminus to terminated. But insofar as time or the 'now' numbers things, it numbers things other than time. The reason [ratio] for this is that there is a terminus only of that which is terminated. But numbers are of diverse things; thus, ten is the number of horses and other things. Therefore the 'now' is the terminus only of time, but it is the number of all mobile objects which are moved in time.