As I feel it a duty to reserve, for other purposes, the very small power of work now left to me, I am obliged to decline entering upon a controversy. I must leave readers to examine for themselves—little hoping, however, that they will do so. One point only I wish to note. The use of the expression “forms of thought,” instead of “forms of intuition,” was simply an inadvertence; as will be manifest on observing that though I have used the wrong expression in the note, I have used the right expression in the text (p. 203), as also throughout my criticism of Kant’s doctrine in _The Principles of Psychology_, Part VII, Chapter IV, “The Reasonings of Metaphysicians,” § 399. HERBERT SPENCER. LOGIC AS RELATION-LORE. In the French _Revue Philosophique_, in the August and September 1891 numbers of the same, M. George Mouret has an essay entitled “Mathematical Equality” in the course of which and as though subsidiary to his ostensible purpose he discourses upon the topics of relations and concepts and upon the fundamental elements of logic in general. His essay is really more important as a contribution to logical doctrine than as a treatment of mathematical equality. The scope of his discourse will be seen by reference to his closing paragraphs in which he sums up what he considers to be the results achieved by him in his essay. Therein, he says that he has “treated of the general theory of the composition of concepts and relations and set the foundations of the logic of analysis and the logic of definition.” I. THE SPENCERIAN AXIOM. The determining factor of every philosophical dissertation is of course some very general supposition which is taken as established and which exercises a controlling influence over all the observations of its author. In this case this determining supposition is found in what M. Mouret calls his “_axiom_ of _symmetry_.” The same is thus stated by him “_Two things which have the same symmetrical relations to a third thing have between them that same relation._”