parallelist hypothesis loses every sort of meaning. It ceases to present to us the image of two phenomena of an absolutely different order, which are found coupled together like the two faces of a unity, the front and back of a page, the right and wrong side of a stuff. If there is anything material in the psychical part, the opposition of nature no longer exists between the two terms; they become identical.
Very often, certain parallelists, after thinking they have discovered the duality of nature, endeavour to bring it back to unity by supposing that the two faces of the reality are as two effects of one unique reality, inaccessible to our senses and underlying appearances. Why go so far afield to seek unity? It is trouble in vain: for it is to be found in the phenomenon itself.