Mr. Upton Sinclair, about fifty-two years old when his book _Mental Radio_ was issued, is, as everyone is supposed to know, one of the leading novelists of the United States. His stories are all, or nearly all, characterized by an intense purpose. To those who claim that art should be exercised only for art’s sake this may be obnoxious. But from the point of view of this examination of his book purporting to prove telepathy, the fact that his novels also attempt to prove something, on the basis of studies made by him, is quite in his favor.[4] Whether he has in fact proved the thesis of his respective tales is not within our province to determine; we do propose rigidly to analyze and review his claims to have proved telepathy. Mr. Sinclair is a Socialist, and a very active and prominent one; he has been Socialist candidate for Congress in New Jersey and later in California, besides having been Socialist candidate for the United States Senate and for Governor in the latter-named State. Political prejudices or predilections should be strictly excluded from the minds of readers of the book or this review of it.[5] It is another gratifying indication that Mr. Sinclair was not deterred from publishing _Mental Radio_ by the solicitations or irony of influential friends in his political group, for the scientific spirit is in part compounded of courage, honesty and candor. Mrs. Sinclair, née Mary Craig Kimbrough, somewhere about forty-five years old when the experiments afterwards published took place, is the daughter of a retired judge, bank president, and planter of Mississippi. The reader may judge of the quality of her mentality by reading Appendix 1. That is, in part, the reason that it is printed. It is a piece of writing by Mrs. Sinclair shortened according to permission given. Almost immediately after my suggestion that the experimental materials should be sent for examination, they were bundled up and sent, together with some stray scraps, among which was this unfinished piece of manuscript which, as it proved, the Sinclairs did not know had been included. In spots the composition may be a bit diffuse and repetitious, but the woman really thinks and reasons, which is more than many do. There is in it a sincerity, earnestness and intensity of desire to know, which can hardly be counterfeited. Its writer fairly rivals Descartes in her determination to find some salient and secure spot from which to start in her quest. But in a manner she goes back farther than Descartes, at least she splits his ultimate in two. She is satisfied with “I am,” not because “I think,” but because “I am conscious of thinking”; but she does not so readily grant the “_I_ think.” She wants to know, “Am _I_ doing all the thinking I am conscious of?”