Boris Sidis

“ Mental and physical phenomena are both manifestations of one unitary substance. There is no need for me to point out that this double aspect of one unitary substance belongs to metaphysical dogmatism, of substantialism, and as such cannot possibly be admitted into the province of psychology as a natural science. ”

“ The argument that an idea is sometimes followed by one and sometimes by another idea showing the absence of invariable sequence is, if looked at closer, of a rather dubious character. An idea a or idea b is only objectively the same, by having the same object, but the thought, mental stream, or moment consciousness that possess that idea may not be the same, but it is just this mental stream, the moment-consciousness that determines the content of the succeeding idea. The thought of a is different according to the difference of the mental stream or moment consciousness. ”

“ Now, reasons this school, if psychology is to be a science at all, it must surely be of such a nature as to be communicated to other subjects, that is, it must become common property, and since by definition, only a physical object is an object of many and is communicable, hence a psychic object to become communicable must be expressed in physical terms. ”