But poetry and dramatic writing did not so far engross the thoughts of our author, but that she sometimes turned them to subjects of a very different nature; and at an age when few of the other sex were capable of understanding the Essay of Human Understanding, and most of them prejudiced against the novelty of its principles; and though she was at that time engaged in the profession of a religion not very favourable to so rational a philosophy as that of Mr. Lock; yet she had read that incomparable book, with so clear a comprehension, and so unbiassed a judgment, that her own conviction of the truth and importance of the notions contained in it, led her to endeavour that of others, by removing some of the objections urged against them. She drew up therefore a Defence of the Essay, against some Remarks which had been published against it in 1667. The author of these remarks was never known to Mr. Lock, who animadverted upon them with some marks of chagrin, at the end of his reply to Stillingfleet, 1697. But after the death of the ingenious Dr. Thomas Burner, master of the Charter-House, it appeared from his papers, that the Remarks were the product of his pen. They were soon followed by second Remarks, printed the same year, in vindication of the first, against Mr. Lock's Answer to them; and in 1699, by Third Remarks, addressed likewise to Mr. Lock. Mrs. Trotter's Defence of the Essay against all these Remarks was finished so early as the beginning of December 1701, when she was but 22 years old. But being more apprehensive of appearing before the great writer whom she defended, than of the public censure, and conscious that the name of a woman would be a prejudice against a work of that nature, she resolved to conceal herself with the utmost care. But her title to the reputation of this piece did not continue long a secret to the world. For Mrs. Burnet, the late wife of Dr. Burnet, bishop of Sarum, a lady of an uncommon degree of knowledge, and whose Method of Devotion, which passed through several editions, is a proof of her exemplary piety, and who, as well as that prelate, honoured our author with a particular friendship, notwithstanding the difference of her religion, being informed that she was engaged in writing, and that it was not poetry, was desirous to know the subject. This Mrs. Trotter could not deny a lady of her merit, in whom she might safely confide, and who, upon being acquainted with it, shewed an equal sollicitude that the author might not be known. But afterwards finding the performance highly approved by the bishop her husband, Mr. Norris of Bemmerton, and Mr. Lock himself; she thought the reasons of secrecy ceased, and discovered the writer; and in June 1707 returned her thanks to Mrs. Trotter, then in London, for her present of the book, in a letter which does as much honour to her own understanding, principles and temper, as to her friend, to whom she addressed it. Dr. Birch has given a copy of this letter.