In the summer of 1692 he spent a considerable time in London. His main business there seems to have been to see the _Third Letter on Toleration_ through the press. But he was now, as ever, ready to do work for his friends. Thus he obtained for Limborch the permission to dedicate the book which he had so long been preparing, the _Historia Inquisitionis_, to Tillotson, then Archbishop of Canterbury. Limborch evidently set great store on this privilege. Of Tillotson, Locke seems to have entertained a very high opinion; which, indeed, was thoroughly well deserved. "In proportion to his renown and worth is his modesty." Tillotson was not one of those liberal Churchmen whom promotion makes timid, or cold to their former friends. He was maligned by an unforgiving and unscrupulous faction, more, perhaps, than any other man of that age, but he always retained the courage of his opinions. Locke's health seems to have suffered much during the winter of 1692-93. But he still occupied himself with literary work. While in Holland, he had corresponded frequently with Clarke on the education of his children. Yielding to the solicitation of many of his friends, especially William Molyneux, he now reduced the letters to the form of a treatise, which was published in July, 1693, under the title _Some Thoughts Concerning Education_. The dedication to Clarke bears date in the previous March, and is signed by Locke, though his name does not appear on the title-page. The most serious work, however, in which he was now engaged, was the preparation of a second edition of the _Essay_. The first edition seems to have been exhausted in the autumn of 1692. On the alterations and additions introduced into the second edition, there is an interesting correspondence with Molyneux, ranging from Sept. 20, 1692, to May 26, 1694, when the new edition, notwithstanding the "slowness of the press," was "printed and bound, and ready to be sent" to Locke's Dublin correspondent. Besides suggestions in detail, such as those touching the questions of liberty and personal identity, Molyneux urged Locke to undertake a separate work on Ethics, a suggestion which for a time he entertained favourably, but which, owing partly, perhaps, to his idea that the principles and rules of morality ought to be presented in a demonstrative form, was never carried out. Though he does not seem to have doubted that "morality might be demonstrably made out," yet whether he was able so to make it out was another question. "Every one could not have demonstrated what Mr. Newton's book hath shown to be demonstrable." He was, however, ready to employ the first leisure he could find that way. But the treatise never proceeded beyond a few rough notes. Another reason assigned, at a later period, for not more seriously setting about this task was that "the Gospel contains so perfect a body of ethics, that reason may be excused for that inquiry, since she may find man's duty clearer and easier in revelation than