'I return always to the study of Physics with more pleasure - after trying "The Philosophy of Mind". It is delightful, after wandering in the thick darkness of metaphysics?to behold again the fair face of truth. When will there arise a man who shall do for the science of mind - what Newton did for that of matter - establish its fundamental laws on the firm basis of induction - and discard forever those absurd theories - that so many dreamers have devised? - I believe this is a foolish question - for its answer is - never. - I am led to talk in this manner - by having lately read M[r.] Sweart's [Stewart's] "History of Philosophy" in the supplement to the "Encyclopedia Britannica"[.] I doubt I am going to displease you - but I must say - that I do not recollect of ever having bestowed as much attention with so little effect - upon any author as upon Profr Stewart. Let me study his writings as I like - my mind seems only to turn on its axis - but without progressive or retrograde motion at all.'