“ From the standpoint of orthodox psychology, there are two boundaries between the mental and the physical, namely, sensation and volition. ‘sensation’ may be defined as the first mental effect of a physical cause, ‘volition’ as the last mental cause of a physical effect.” …“What then do we know about the physical world? Let us first define more exactly what we mean by a ‘physical’ event. I should define it as an event which, if known to occur, is inferred, and which is not known to be mental. And I define a ‘mental’ event as one with which some one is acquainted otherwise than by inference. Thus a ‘physical’ event is one which is either totally unknown , or, if known at all, is not known to any one except by inference – or perhaps we should say, is not known to be known to any one except by inference.” Text: Bertrand Russell, Human Knowledge: Its Scope and Limits (1948) Body and Mind, G.N.A. Vesey, ed. George Allen and Unwin, Ltd., London, 1964. Image: Kazimer Malevich, “Black Cross,”, 1923. Collection: Russian State Museum, Saint Petersburg. malevich_black_cross.jpeg dmoma.org

sensation and volition