Аннотация:Bertrand Russell and Arthur Eddington are considered to have inspired Russellian monism by proponents of this key theory of contemporary panpsychism. It is said that they arrived at similar points of view independently from each other. However, a reciprocal influence existed between them as well as quite substantial differences in their ideas. The aim of the article is to clarify the relationship between Russell’s and Eddington’s views on the nature of matter and consciousness, to understand reasons of this state of affairs and its significance for contemporary panpsychism. It is shown that Eddington can be considered as the first proponent or even the very founder of Russellian monism, depending on the interpretations of Russell’s ideas. It is claimed that regardless of the fact that Russellian monism developed definitively and acquired its name only at the turn of the ХХ–ХХI centuries, like contemporary panpsychism as a whole, it has as its source the revolutionary changes that took place in physics during the first third of the ХХ century.