The world of experience, both physical and psychic, is entirely composed of elements - spatial, tactile, accoustical, thermal, etc. Combinations of these elements make up different "phenomena", both psychic and physical. If the law of causality, inferred for all these phenomena - i. e. for the world of elements connected by various relations - is applicable to "things in themselves" serving as an immediate link between "phenomena" and "things", it is clear that "phenomena" and "things in themselves" are of the same nature. "Things in themselves" would then represent a direct continuation of the world of empirical elements and in fact would be only combinations of elements.

Bogdanov, A. A in: James Patrick Scanlan, (1965). : Pre-revolutionary philosophy and theology. Philosophers in exile. Marxists and Communists. p. 398