By I. D’ISRAELI.

Nothing is so capable of disordering the intellects as an intense application to any one of these six things: the Quadrature of the Circle; the Multiplication of the Cube; the Perpetual Motion; the Philosophical Stone; Magic; and Judicial Astrology. In youth we may exercise our imagination on these curious topics, merely to convince us of their impossibility; but it shows a great defect in judgment to be occupied on them in an advanced age. “It is proper, however,” Fontenelle remarks, “to apply one’s self to these inquiries; because we find, as we proceed, many valuable discoveries of which we were before ignorant.” The same thought Cowley has applied, in an address to his mistress, thus:

The same thought is in Donne. Perhaps Cowley did not suspect that he was an imitator. Fontenelle could not have read either; he struck out the thought by his own reflection. It is very just. Glauber searched long and deeply for the philosopher’s stone, which though he did not find, yet in his researches he discovered a very useful purging salt, which bears his name.

Maupertuis, in a little volume of his letters, observes on the “Philosophical Stone,” that we can not prove the impossibility of obtaining it, but we can easily see the folly of those who employ their time and money in seeking for it. This price is too great to counterbalance the little probability of succeeding in it. However it is still a bantling of modern chemistry, who has nodded very affectionately on it. Of the “Perpetual Motion,” he shows the impossibility, at least in the sense in which it is generally received. On the “Quadrature of the Circle,” he says he can not decide if this problem be resolvable or not; but he observes, that it is very useless to search for it any more; since we have arrived by approximation to such a point of accuracy, that on a large circle, such as the orbit which the earth describes round the sun, the geometrician will not mistake by the thickness of a hair. The quadrature of the circle is still, however, a favorite game of some visionaries, and several are still imagining that they have discovered the perpetual motion; the Italians nick-name them matto perpetuo; and Bekker tells us of the fate of one Hartmann, of Leipsic, who was in such despair at having passed his life so vainly in studying the perpetual motion, that at length he hanged himself.