Newton, of whom it was truly said that his mind conquered the human race, was in old age afflicted by mental disorder, though of a less serious character than that of which we have just read. It was probably during this illness that he wrote his _Chronology_, his _Apocalypse_, and the _Letters to Bentley_, so inferior in value to the work of his earlier years. In 1693, after his house had been burnt a second time, and after excess in study, he is reported to have talked so strangely and incoherently to the archbishop that his friends were seriously alarmed. At this time he wrote two letters which, in their confused and obscure form, seem to show that he had been suffering from delusions of persecution. He wrote to Locke (1693): “Being of opinion that you endeavoured to embroil me with women, and by other means, I was so much affected with it, as that when one told me you were sickly and would not live, I answered, ’twere better if you were dead. I desire you to forgive me this uncharitableness; for I am now satisfied that what you have done is just, and I beg your pardon for my having hard thoughts of you for it, and for representing that you struck at the root of morality, in a principle you laid in your book of ideas, and designed to pursue in another book, and that I took you for a Hobbist. I beg your pardon also for saying or thinking that there was a design to sell me an office or to embroil me. I am your most humble and unfortunate servant, Is. Newton.”[172] Locke replied kindly, and a month later Newton again wrote to him: “The last winter, by sleeping too often by my fire, I got an ill habit of sleeping; and a distemper, which this summer has been epidemical, put me further out of order, so that when I wrote to you I had not slept an hour a night for a fortnight together, and for five days together not a wink. I remember I wrote to you, but what I said of your book I remember not.” And in a letter to Pepys he says that he has “neither ate nor slept this twelvemonth, nor have my former consistency of mind.”[173] Those who, without frequenting a lunatic asylum, wish to form a fairly complete idea of the mental tortures of a monomaniac, have only to look through Rousseau’s works, especially his later writings, such as the _Confessions_, the _Dialogues_, and the _Rêveries_. “I have very ardent passions,” he writes in his _Confessions_, “and while under their influence, my impetuosity knows no bounds; I think only of the object which occupies me; the entire universe besides is nothing to me; but this only lasts a moment, and the moment which follows throws me into a state of prostration. A single sheet of fine paper tempts me more than the money to buy a ream of it. I see the thing and am tempted; if I only see the means of acquiring it I am not tempted. Even now, if I see anything that tempts me, I prefer taking it to asking for it.”