Page:Mind (New Series) Volume 9.djvu/408

 394 CBITICAL NOTICES : as I am able to revive it at any time in immediate juxtaposition with any other idea I happen to have in mind at the moment. Mr. Petzoldt has then reached the following conclusion, that no psychical act can be understood from a consideration of the psychical acts immediately preceding it, and this leads him at once to the main result of all this preliminary inquiry. These psychical acts must be determined somehow, and as they can- not be determined by mental determining-means, they must be determined by material determining - means. Psychophysical parallelism of the strictest kind must be accepted as a fact or the science of mind be forsaken as a fiction. As mental processes can only be scientifically understood in the light of brain processes, it follows logically that we can under- stand the life of mind only in so far as we have understood the life of the brain. This startling inference is accepted in these very terms by Mr. Petzoldt (p. 90). The Psychologist has two fundamental tasks before him. Firstly, to investigate the life of the brain itself as it exists within its material surroundings, and quite independently of its connexion with the mind ; and secondly, to show in detail how the various psychical processes can be scientifically understood through their dependence on the processes of the brain. These tasks were undertaken for the first time by Richard Avenarius. The first problem he solves in the first volume of the Critique, and in the second volume he solves the second. It is at this point no doubt that the reader who is not already familiar with the work of Avenarius will have his interest and curiosity excited in the highest degree. He will naturally expect, first, some brilliant physiological or biological discovery ; and then, founded upon this, some equally impressive solution of the relation of Body to Mind none the less acceptable for being previously unimaginable. But all this is vain expectation. Avenarius did not make physiological discoveries, and he is no nearer than was Spinoza to the solution of the great enigma. Avenarius was a psychologist. His theory of brain-processes is a mere translation into material terms of his theory of mental processes, and alas ! to any one who, despite all the arguments of Mr. Petzoldt, still believes that the mind contains its own principles of determina- tion, this whole laborious, ingeniously-elaborated translation is completely superfluous. To justify this disillusionment, we need not go beyond Mr. Petzoldt's own statements. For on page 93 we read that the two great discoveries in question were made by Avenarius as a result of an unprejudiced investigation not of cortical but of mental processes. The discoveries in fact were of a purely psychological nature, and as such they are both very interesting in themselves and very thoroughly worked out by their discoverer. The first is the discovery that our psychical life at any moment consists in the play of a number of more or less easily distinguishable