You do not believe in absolute truth, and I no more hope for it. The mind does not escape certain illusions, which come from what it necessarily places in the reality that it wishes to know, or which it acquires from itself. Meanwhile both the opposing doctrines triumph, seeing that there is always something in each that cannot be explained; but let them not be too severe on each other, and not forget that if they succeed in explaining something, it is perhaps as well that they resign themselves to not explaining everything. I had intended to give in this letter a detail of the theory of Mme. CLÉMENCE ROYER, in order to compare it with that of M. Fouillée; I had prepared it from certain published memoirs, as her great manuscript work has unfortunately not found a publisher. But _The Open Court_ has given a résumé of it sufficiently complete to excuse me from returning to the subject. Whatever service can be rendered by the hypothesis of Mme. Clémence Royer, or, more strictly whatever use can be made of the mathematical formulæ which explain them, or which are deducible from them, it will belong to special scientists to inform us. She begins the explanation of the world by physics, and M. Fouillée by psychology. It is a difference in the point of departure. Let us add that M. Fouillée appears to imagine an activity without substance, a mind without muscles, if it can be thus expressed; on the contrary, in that which she calls world-stuff Mme. Clémence Royer distinguishes a hyperethereal or vital state, and she assigns for the substratum of life this simple state of the cosmical substance. Opposed as may be the character of the minds of these two authors, the two theories seem to coincide in the notion of a living and conscious monad. We meet it when they are farthest apart! Thus, for Mme. Clémence Royer, life and consciousness are everywhere, they are in the atom, and from the beginning. There, in the great "romance of being," is a scene which reappears almost always the same. As to the ultimate explanation we have no great choice, and each of the hypotheses that we form almost produces the other. All the value of a system of philosophy is really in the help it lends to scientific curiosity or to the conduct of life. * * * * * M. ERNEST NAVILLE is one of those who cannot comprehend moral conduct in life apart from spiritualism. He endeavors, accordingly, in a work called _La Physique Moderne_, to prove that the study of the phenomena of matter does not imply materialism and does not necessarily lead to atheism. The argument of M. Naville is well worn. We shall grant to him only that "it is necessary to avoid implicitly solving questions by saying that we do not deal with them at all." On the whole, this pledges to nothing. Practically, and in good faith, abstention is nevertheless a solution. * * * * *