Chapter XI. Concerning Geometry, and Astronomy, and Syllogisms. From Xenophon’s Memorabilia

[XENOPHON] ‘HE also used to teach how far it was necessary for a well-educated man to be acquainted with each subject. For example, he said that he ought to learn geometry so far as to be able, if ever it should be necessary, rightly to measure land either in taking or giving possession, or in allotting it, or marking out work. And this, he said, was so easy to learn that one who gave his mind to the measuring could know at once how much land there was, and go away acquainted with the mode of measuring it.

‘But of learning geometry so far as to reach those unintelligible diagrams he disapproved, for he said he did not see of what use these were, although he was not unacquainted with them. But they were enough, he said, to exhaust a man’s lifetime, and hindered him from many other useful branches of learning.

‘He bade them also become acquainted with astronomy, but this also only so far as to be able to know the time of night, or of the month, or of the year, for the sake of travelling, or voyaging, or keeping watch, and to be able to make use of the indications relating to all other things that are to be done either in the night, or in the month, or year, by knowing the different seasons for the works before mentioned. These also, he said, were easy to learn from nocturnal hunters, and pilots, and many others, whose business it is to know these things.

‘But he strongly dissuaded from learning astronomy to such an extent as to know the bodies which are not in the same orbit, and the planets and comets, and to waste time in investigating their distances from the earth, and their periods, and the causes of them. For he said that in these matters he did not see any benefit, and yet even in these he was not uninstructed. But he said of these also that they were enough to wear out a man’s lifetime, and to hinder him from many useful pursuits.

‘And he wholly dissuaded one from anxiously inquiring in what way the heavenly bodies are each contrived by God; for he neither thought that these things could be discovered by mankind, nor did he believe that the gods would be pleased with the man who sought to know what they had not been willing to make clear. But he said that the man who troubled himself about these things would be in danger even of going as mad as Anaxagoras was, who prided himself very highly upon explaining the contrivances of the gods.

‘For when he used to say that fire and the sun were the same, he ignored the fact that though men easily discern, the fire, yet they cannot look upon the sun; and by being exposed to the sunshine they have their complexions darkened, but not so by fire. Also he was ignorant that of plants which spring out of the earth none can make good growth without the light of the sun, while all perish when heated by fire. And in saying that the sun was a fiery stone he was ignorant also of this fact, that while a stone set in the fire neither shines nor lasts long, the sun continues all the time to be the brightest of all things.

‘He also used to bid us learn to count; but here also as in everything else he bade us guard against useless trouble: yet as far as it was useful he would himself help his companions in examining and discussing all things.’

So writes Xenophon in the Memorabilia.And in the Epistle to Aeschinesthe same author writes as follows concerning Plato, and those who boast of their physiology of the universe: [1]