by Aristotle
26 · Why is it more difficult to carry a long plank of wood on the shoulder if [5] one holds it at the end than if it is held in the middle, though the weight is the same? Is it because, as the plank vibrates, the end prevents one from carrying it, because it tends to interrupt one’s progress by its vibration? No, for if it does not bend at all [10] and is not very long, it is nevertheless more difficult to carry if it is held at the end. It is easier to carry if one holds it in the middle rather than at the end, for the same reason for which it is easier to lift in that way. The reason is that, if one lifts it in the middle, the two ends always lighten one another, and one side lifts the other side up. For the middle, where the lifter or carrier holds it, forms, as it were, the centre, and [15] each of the two ends inclining downwards raises up and lightens the other end; whereas if it is lifted or carried from one end, this effect is not produced, but all the weight inclines in one direction. Let A be the middle of a plank which is raised or carried, and let B and C be the extremities. When the plank is lifted or carried at the point A, B inclines downwards and raises C up, and C inclines downwards and [20] raises B up; the effect is produced by their being raised up at the same moment.
27 · Why is a very long object more difficult to carry on the shoulder, even if one carries it in the middle, than a shorter object of the same weight? In the last case we said that the vibration was not the reason; in this case it is the reason. For [25] the longer an object is, the more its extremities vibrate, and so it would be more difficult for the man to carry it. The reason of the increased vibration is that, though the movement is the same, the extremities change their position more the longer the piece of wood is. Let the shoulder, which is the centre (for it is at rest), be at A, and [30] let AB and AC be the radii; then the longer the radius AB or AC is, the greater is the amplitude of movement. This point has already been demonstrated.
28 · Why do they construct swing-beams by the side of wells by attaching the lead as a weight at the end of the bar, the bucket being itself a weight, whether it [35] is empty or full? Is the reason that, the drawing of water being divided into two operations distinct in time (for the bucket has to be dipped and then drawn up), it is an easy task to let it down when it is empty, but difficult to raise it when it is full? It [857b1] is therefore of advantage to lower it rather more slowly with a view to lightening the weight considerably when it is drawn up again. This effect is produced by the lead or stone attached to the end of the swing-beam. In letting it down there is a heavier [5] weight to lift than if one has merely to lower the empty bucket; but when it is full, the lead, or whatever the weight attached is, helps to draw it up; and so the two operations taken together are easier than on the other method.
29 · Why is it that when two men are carrying an equal weight on a piece of wood or something of the kind, the pressure on them is not equal unless the weight is [10] in the middle, but it presses more on the person carrying it to whom it is nearest? is it because the wood, when they hold it in this way, becomes a lever, and the load [15] forms the fulcrum, and the carrier nearer to the load becomes the weight which is to be moved, while the other carrier becomes the mover of the weight? The further the latter is from the weight, the more easily he moves it, and the more he presses down the other man, since the load placed on the wood and acting as a fulcrum, as it were, offers resistance. But if the load is placed in the middle, one carrier does not act as a weight on the other any more than the other on him, or exercise any motive force [20] upon him, but each is equally a weight upon the other.
30 · Why is it that when people rise from a sitting position, they always do so by making an acute angle between the thigh and the lower leg and between the chest and the thigh, otherwise they cannot rise? Is it because equality is always a cause of rest, and a right angle causes an equality and so causes equilibrium? So in [25] rising a man moves towards a position at equal angles to the earth’s circumference; for it is not the case that he will actually be at right angles to the ground. Or is it because when a man rises he tends to become upright, and a man who is standing must be perpendicular to the ground? If, then, he is to be at right angles to the [30] ground, that means that he must have his head in the same line as his feet, and this occurs when he is rising. As long, then, as he is sitting, he keeps his feet and head parallel to one another and not in the same straight line. Let A be the head, AB the line of the chest, BC the thigh, and CD the lower leg. Then AB, the line of the chest, [35] is at right angles to the thigh, and the thigh at right angles to the lower leg, when a man is seated in this way. In this position, then, a man cannot rise; but to do so he must bend the leg and place the feet at a point under the head. This will be the case if CD be moved to CF, and the result will be that he can rise immediately, and he [858a1] will have his head and his feet in the same straight line;8 and CF will form an acute angle with BC.
31 · Why is it that a body which is already in motion is easier to move than one which is at rest? For example, a wagon which is in motion can be propelled more [5] quickly than one which has to be started. Is it because, in the first place, it is very difficult to move in one direction a weight which is already moving in the opposite direction? For though the motive force may be much quicker, yet some of it is lost; for the propulsion exerted by that which is being pushed in the opposite direction must necessarily become slower. And so, secondly, the propulsion must be slower if the body is at rest; for even that which is at rest offers resistance. When a body is [10] moving in the same direction as that which pushes it, the effect is just as if one increased the force and speed of the motive power; for by moving forward it produces of itself exactly the effect which that power would have upon it.
32 · Why is it that an object which is thrown eventually comes to a [15] standstill? Does it stop when the force which started it fails, or because the object is drawn in a contrary direction, or is it due to its downward tendency, which is stronger than the force which threw it? Or is it absurd to discuss such questions, while the principle escapes us?
33 · How is it that a body is carried along by a motion not its own, if that which started it does not keep following and pushing it along? Is it not clear that in the beginning the impelling force so acted as to push one thing along, and this in its turn pushes along something else? The moving body comes to a standstill when the force which pushes it along can no longer so act as to push it, and when the weight of [20] the moving object has a stronger inclination downwards than the forward force of that which pushes it.
34 · Why is it that neither small nor large bodies travel far when thrown, but they must have due relation to the person who throws them? Is it because that [25] which is thrown or pushed must offer resistance to that from which it is pushed, and whatever does not yield owing to its mass, or does not resist owing to its weakness, does not admit of being thrown or pushed? A body, then, which is far beyond the force which tries to push it, does not yield at all; while that which is far weaker offers no resistance. Or is it because that which travels along does so only as far as it [30] moves the air to its depths, and that which is not moved cannot itself move anything either? Both these things are the case here; that which is very large and that which [858b1] is very small must be looked upon as not moving at all; for the latter does not move anything, while the former is not itself at all moved.
35 · Why is it that an object which is carried round in whirling water is [5] always eventually carried into the middle? Is it because the object has magnitude, so that it has position in two circles, one of its extremities revolving in a greater and the other in a lesser circle? The greater circle, then, on account of its greater velocity, draws it round and thrusts it sideways into the lesser circle; but since the object has breadth, the lesser circle in its turn does the same thing and thrusts it into [10] the next interior circle, until it reaches the centre. Here the object remains because it stands in the same relation to all the circles, being in the middle; for the middle is equidistant from the cir
cumference in the case of each of the circles. Or is it because an object which, owing to its magnitude, the motion of the whirling water cannot [15] overcome, but which by its weight prevails over the velocity of the revolving circle, must necessarily be left behind and travel along more slowly? Now the lesser circle travels more slowly—for the greater and the lesser circle do not9 revolve over the same space in an equal time when they move round the same centre—and so the object must be left revolving in a lesser and lesser circle until it reaches the middle. [20] If the force of the whirling water prevails at first, it will go on doing so to the end; for one circle must prevail and then the next over the weight of the object owing to their velocity, so that the whole object is continually being left behind in the next circle towards the centre. For an object over which the water does not prevail must be carried either inwards or outwards. Such an object cannot then be carried along in [25] its original position; still less can it be carried along in the outer circle, for the velocity of the outer circle is greater. The only alternative is that the object over which the water does not prevail is transferred to the inner circle. Now every object [30] has a tendency to resist force; but since the arrival at the middle puts an end to motion, and the centre alone is at rest, all objects must necessarily collect there.
**TEXT O. Apelt, Teubner, Leipzig, 1888
1Reading τò μὲν A.
2Omitting κατ’ εὐθεῖαν.
3Placing a comma after, not before, ἐπὶ τò μέσoν.
4Reading διó for ὅ.
5Placing a comma after, not before, καἱ ὁ σταθμóς.
6Omitting ὑφ’ ὧν.
7Placing a comma after καὶ ὁ μείζων, and reading ὁπoτερωσoῦν.
8Reading εὐθείας.
9Reading oὐ τò αὐτó.
PROBLEMS**
E. S. Forster
BOOK I
PROBLEMS CONNECTED WITH MEDICINE
1 · Why is it that great excesses cause disease? Is it because they engender [859a1] excess or defect, and it is in these after all that disease consists?
2 · But why is it that diseases can often be cured if the patient indulges in excess of some kind? And this is the treatment used by some doctors; for they cure [5] by the excessive use of wine or water or salt, or by over-feeding or starving the patient. Is it because the causes of the disease are opposites of one another, so that each reduces the other to the mean?
3 · Why is it that the changes of the seasons and the winds intensify or stop [10] diseases and bring them to a crisis and engender them? Is it because the seasons are hot and cold and moist and dry, while diseases are due to excess of these qualities and health to their equality? In that case, if the disease is due to moisture or cold, a season which has the opposite characteristics stops it; but if a season of the opposite kind follows, the same admixture of qualities being caused as before intensifies the disease and kills the patient. For this reason the seasons even cause disease in [15] healthy persons, because by their changes they destroy the proper admixture of qualities; for it is at the same time improved by suitable seasons, times of life, and localities. The health therefore requires careful management at times of change. And what has been said generally as to the effect of the seasons applies also in detail; for changes of winds and of age and of locality are to some extent changes of [20] season. These also therefore intensify and stop diseases and bring them to a crisis and engender them, as do the seasons and the risings of certain constellations, such as Orion and Arcturus and the Pleiads and the Dogstar, since they cause1 wind and rain and fine weather and storms and sunshine.
[25] 4 · Why ought emetics to be avoided at the changes of the seasons? Is it in order that there may be no disturbance when the excretions are being altered by such changes?
[859b1] 5 · Why is it that the feet swell both of those who are bilious and of those who are suffering from starvation? Is it in both cases the effect of wasting? For those who are starving waste because they do not receive any nourishment at all, while the bilious waste because they do not derive any benefit from the nourishment which they take.
[5] 6 · Why is it that, though the diseases due to bile occur in the summer (the season when fevers are at their height), acute diseases due to bile occur rather in the winter? Is it because, being accompanied by fever, they are acute because they are violent, and violence is unnatural? For fervent inflammation is set up when certain parts of the body are moist, and inflammation, being due to an excess of heat, [10] engenders fevers. In the summer, therefore, diseases are dry and hot, but in the winter they are moist and hot and consequently acute (for they soon kill the patient), for concoction will not take place because of the abundance of the excretion.
[15] 7 · Why is it that the plague alone among diseases infects particularly persons who come into contact with those who are under treatment for it? Is it because it is the only disease to which all men alike are liable, and so the plague affects any one who is already in a low state of health? For they quickly become infected by the inflammatory matter caused by the disease which is communicated [20] by the patient.
8 · Why is it that, when north winds have been prevalent in the winter, if the spring is rainy and characterized by south winds the summer is unhealthy with fever and ophthalmia? Is it because the summer finds the body full of alien humours, and [25] the earth, and any place in which men dwell, becomes moist and resembles localities which are regarded as permanently unhealthy? The result is that, first, ophthalmia occurs when the excretion in the region of the head liquefies, and, secondly, fever [860a1] ensues. For it is noticeable that anything which admits of extreme cold also admits of extreme heat,—water, for example, and a stone, of which the former boils quicker than other things, the latter burns more.2 As, therefore, in the air a stifling heat occurs when it grows warm owing to its density, so likewise in the body stifling [5] and heat are engendered, and heat in the body is fever and in the eyes ophthalmia. Generally speaking the change which occurs when a warm, dry summer follows immediately on a wet spring, being violent has a deleterious effect upon the body. The effect is still worse if the summer is rainy; for then the sun finds material, which [10] it will cause to boil in the body as in the earth and air; the result is fever and ophthalmia.
9 · Why is it that, if the winter is characterized by south winds and rainy and if the spring is dry with the wind in the north, both the spring and the summer are unhealthy? Is it because in the winter owing to the heat and moisture the body assimilates its condition to that of the season, since it must necessarily be moist and [15] relaxed? When the body is in this state, the spring being cool congeals and hardens it owing to its dryness. The result is that women who are pregnant run a risk of abortion in the spring because of the inflammation and mortification caused by the dry cold, since the necessary moisture is not secreted, and the foetus in the womb [20] becomes weakly and defective owing to the excess of cold; for children who are born at this season in fine weather become strong and receive nourishment in the womb. In the case of other persons—because in the spring the phlegm is not purged away owing to its excess (as happens when the weather is warm), but congeals owing to [25] the cold—when the summer and warmth succeeds, setting up violent liquefaction, humours form in those who are bilious and dry because their bodies lack moisture and are naturally parched; but these humours are slight and so such people suffer from dry ophthalmia. Those on the other hand who are phlegmatic are afflicted [30] with sore throats and catarrh of the lungs. Women suffer from dysentery owing to their natural moisture and cold; while elderly persons are afflicted with apoplexy, when moisture being all set free at once overcomes them and solidifies owing to the weakness of their natural heat.
10 · Why is it that, when the summer is dry and northerly winds prevail and [35] the autumn on the contrary is wet and characterized by south winds, headaches and sore throats and coughs occur in the ensuing winter and then terminate in phthisis? Is it b
ecause the winter finds a considerable amount of matter in the body and so it [860b1] is a difficult task for it to solidify the moisture and form phlegm? Consequently, when moisture is engendered in the head, it causes a feeling of heaviness, and if it is plenteous and cold, it causes mortification; but if, owing to its abundance, it does [5] not solidify, it flows into the nearest region of the body, and thus coughs are caused and sore throats and wasting.
11 · But why is it that if the summer and autumn are dry and northerly winds prevail, this weather suits those who are phlegmatic, and women? Is it because in both cases nature tends to an excess in one direction, and so the season [10] exerting its influence in the opposite direction establishes an equable temperament, and they are healthy at the time, unless they themselves do anything which harms them, and, when the winter comes on, they are not in a moist condition, having heat in them with which to resist the cold?