4. When he had said this, he desired me to contribute something to the discourse; and I applauded their conceits as their own devices, and very probable. But lest you despise yourselves (I continued) and altogether look for some external explication, attend to an exposition upon this sentence, which your masters very much approve. Amongst the most geometrical theorems, or rather problems, this is one: Two figures being given, to construct a third, which shall be equal to one and similar to the other. And it is reported that Pythagoras, upon the discovery of this problem, offered a sacrifice to the Gods; for this is a much more exquisite theorem than that which lays down, that the square of the hypothenuse in a right-angled triangle is equal to the squares of the two sides. Right, said Diogenianus, but what is this to the present question? You will easily understand, I replied, if you call to mind how Timaeus divides that which gave the world its beginning into three parts. One of which is justly called God, the other matter, and the third form. That which is called matter is the most confused subject, the form the most beautiful pattern, and God the best of causes. Now this cause, as far as possible, would leave nothing infinite and indeterminate, but adorn Nature with number, measure and proportion, making one thing of all the subjects together, equal to the matter, and similar to the form. Therefore proposing to himself this problem, he made and still makes a third, and always preserves it equal to the matter, and like the form; and that is the world. And this world, being in continual changes and alterations because of the natural necessity of body, is helped and preserved by the father and maker of all things, who by proportion terminates the substance according to the pattern. Wherefore in its measure and circuit this universal world is more beautiful than that which is merely similar to it.... _QUESTION III._ WHY NOISES ARE BETTER HEARD IN THE NIGHT THAN THE DAY. AMMONIUS, BOETHUS, PLUTARCH, THRASYLLUS, ARISTODEMUS.