Abstract
May discovered Diderot's copiously annotated copy of this anti-materialist tract by Hemsterhuis, known to many contemporaries as "the Dutch Plato"; this edition contains May's interesting introduction, a facsimile of the original text, and a transcription of all of Diderot's comments. The comments bear on infelicities of style as well as of thought, though the latter preponderate: the Lettre is not, alas, the product of a first-rate philosophical intellect. Diderot's strong objections to Hemsterhuis' crude theory of a moral organ can be taken as complementing his Refutation of Helvetius, which dates from the same period.—W. L. M.