Boris Sidis

“ Without the help of the concomitant physiological series the investigator of the psychic process is, scientifically considered, completely helpless, since the psychic process has no objectively necessary causal interconnection.
The "Voluntaristic" school in attempting to make of psychology a science independent of all physiology is fundamentally wrong. Without the physiological series psychology has no cement to fasten its material with, it has no foundation to build on. ”

“ Taking the psychic process from the ontogenetic standpoint, we find again the same thing. If the psychic life of the individual is taken as a whole and traced backward, in the past, we arrive at some point, when the i stream of consciousness begins, and on following it forward, we finally arrive at a point where the stream of consciousness ends. ”

“ In other cases, such for instance, as unconsciousness of epilepsy, the stream of consciousness is interrupted and resumed only after a certain period of time, not even the subconscious can supply us the missing link. In normal sleep we meet once more with an interruption of the current of consciousness, and it is only under certain conditions, such as dreaming, that the subconscious can supply the missing states. ”

“ If we view the question phylogenetically, we come once more to the same conclusion. In the history of biological evolution there was a time when psychic life began, and there will come a time when all psychic life will disappear from our globe. ”