Tetrabiblos (The Quadripartite Book)

...are unable to attain the due understanding of this science. Wherefore it is manifest that when a man studies in the quadrivial sciences with great will, rightly, and with all his power, error will happen to him in many things—not because of such reasons as we have discussed, but because of the nature of the thing in which he studies, which is great in itself, and much because of the weakness of the human intellect, which cannot attain all things that are in that science, because it is very great.

After he stated the reasons because of which many believed that this science cannot be attained, and destroyed those opinions—in that he showed that the defects which they find in this science do not belong to the science, but come from the weakness of those who meddle in it—and he had already said to you before that in this science error can happen because of the matter receiving the power of the stars, which is not firm or stable, and that it is very difficult to know the opinion which is made from the conjunction of the powers of the stars: now, however, he wishes to destroy the doubt and show us that this error is not because of a defect which exists in the nature of the science, but because the thing is very difficult in itself, and the human intellect does not have so great a power that it can understand things that are very difficult. Although it is in itself very true—these are the quadrivial sciences, which are truer than all other arts and have firmer demonstrations, because no doubt can exist there—nevertheless, many can err in them, not because of a defect in the science, but because of its great difficulty and the weakness of the human intellect. And since this happens in arithmetic, geometry, music, and the quadrivial astronomy, it is no wonder if the same thing happens in the astrology of judgments, and especially because the matter is not firm or stable, and because of the difficulty of understanding the opinion which is made from the mixture of the stars. And since it is so, the error which happens in this science will not be because of a defect in it, but because of the weakness of the human intellect, which cannot attain to the comprehension of all things that are very difficult.

It also happens generally that we do not truly attain to any quality of these matters in an opinable way. But rather to that which is gathered from many dissimilar things. And generally I say that the state of this matter cannot be directed so that it is totally attained by a way that is very certain, in which there is no doubt, except by the subtlety of the intellect of some who can consider things more sharply than others, and especially in those things which are composed of many and diverse things.

Ptolemy teaches us in this occasion, with manners of art, that everything that we can know about the state of this higher matter is not directed so that it may be known except by the subtlety of the intellect of one more than another, and by the subtle consideration of some; because this matter does not consist always in one state, nor is it firm. And Hippocrates taught us this same thing in physics when he said that time is acute; he wished to say: this matter is not for a long time in one state, but it is quickly changed from one hour to another. But when Ptolemy said in those things which are composed of many and diverse things, he wishes to say: because of the science which is accepted because of the conjunction of many and diverse powers, and because of this it is very difficult to understand the certain opinion which is made through such things. Just as Hippocrates said that judgment is difficult: he wishes to say that every known thing, unless experience approves it, is not so firm that a man ought to trust in operating through it.

In the statement of Ptolemy, however, there are two words which we must gloss, and these are: to consider and to think. According to the ancient logicians, it is in three manners. One is certain in itself, about which nothing else can exist; or concerning this, because a man cannot know for certain, but he thinks that it is so. Another is a thing which is very far from truth and certainty. Another manner is that which is between these two. Whence I say that to think, which Ptolemy said here, is that which is well about that truth about which nothing else can exist, because its certainty is demonstrated by the demonstration noted before. Consideration, however, is another thing well about truth, and this is every thing having a rule which guards it from error, just as a figure which a man makes by a compass and a ruler of wood; for the compass and the ruler make a figure by certain consideration, because it is not made by demonstration. And there is another which is far from truth, and this is a thing happening fortuitously to some of that which a man considers. And there is another which is between these both. But when we shall return to that which we discussed before, you will find that the consideration of this science is that which is well about the truth, because it is a thing which is added to science from the side of certain demonstration. And since it is so, that science is guarded from every error; and when you interpret well what we have said, you will find that through this manner of thinking and considering, the operation of all sciences is made, and especially of physics.

It happens also with this that the figures of the wandering stars formed in ancient times are those through which we consider the figures of our own times which are assimilated to them, and upon their effects, we judge that which men of first authority, inspectors of things, discovered through the figures of their own time, which perhaps they assimilate to the figures of ours much or little because of their long circuits. But that these figures absolutely assimilate to them, such that those things which are in the heavens, just as those which are in the earth, should return to that which they were then, is not at all possible, nor can it be said by anyone unless he be foolish, who perfectly, while mocking, professes to know that which could never be perfectly known by anyone, or who says that he has arrived at that point to which no mortal life has sufficed.

And it happens similarly in this, that it can be that the partitions which the planets have through figures in works which were experimented in ancient times differ much, and we judge these things which the ancient sages said, who were experimented and found it to be so, and they assimilate to the figures of our time, one more and another less because of the long revolutions of the courses of the planets which were from then until this time; nevertheless, to assimilate that which the ancient sages said and experimented to the figures and works of this time with a complete similitude, in which there is no diversity or change, such that everything which is in heaven with everything which is in earth has returned to that same first state, is a thing which cannot be. Nor can anyone praise himself that he attains it, nor can he know a thing from those which cannot be completely attained, nor from those which his life cannot attain, because the life of man is determined.

After he made us understand that the things which we attain in this art, we attain by a consideration which is about demonstration, and that it does not fail to state it except because the matter is not stable, he wishes now to explain more to those who wish to predict in this art, so that no reason remains, saying thus: that those things which we judge at this time through the property of the stars in the matter which is now found, we have from the rectifications of the ancients, and not from another part. And because of this, it happens that there will be such a stellation and such a matter which will assimilate to those which were in the time of the ancient sages, one more and another less, and this because of the revolutions of the stars coming from long times. However, to find such a matter and such a constellation which is the same identical one which the ancient sages certified, such that it is not more or less, is a thing which cannot be, nor can a man in his whole life attain it, because life is determined, nor because of another doctrine. And this is not because of the errors which fall into doctrines; and in long times, it does not befit a man seeking truth to praise himself about such a thing, unless he is one who wishes to show himself to a populace that understands nothing of wisdom. And since it is so, it is no wonder if some error falls in wanting to equate things which are things in this time in heaven and earth to things which were in the time of the ancient sages from such long times until now. But with this statement, he destroyed the opinions of some saying that all things return to the head of the time of things known, with such things as they were another time, neither more nor less, but the very same. And they fell into this error because of the long courses and many revolutions of the stars, because they thought that there is a common number of the years of the world and of the days with which the places of the planets and stars can be certified. And when that is completed, all the stars will have returned to that same point, and because of this all things will return to be such as they were in that same time. In this error, indeed, many...