The Paradox of Causation
But though the composition or structure of matter is thus too obscure a problem to serve as a support for materialism— so that even if everything is made of matter we are, metaphysically or in the search for comprehension, no further advanced, since we cannot say what matter is—it may still seem that the operation of matter is comprehensible and clear.
The behaviour proper to matter is that controlled by causality ; its motions are due not to its own spontaneous initiation but to external compulsive causes.
Matter, if we cannot define it by its structure, can at least be defined as the field in which efficient causes are operative, in which we find the nexus of cause and effect universally maintained. We must turn therefore to this conception of causality, to see how far it will serve as an ultimate principle of explanation.