hand, the effect of the impact of the engine, and is, on the other hand,
the "cause" of the motion of the second car. And, in general, what is an
"effect" in the first car becomes a "cause" when looked at in relation
to the second, and what is an "effect" in the second becomes a "cause"
in relation to the third. So that even the materialist will agree that
"cause" and "effect" are relative terms in dealing with any series of
facts in Nature.

[Sidenote: A Common Platform for All]

A man may be either a spiritualist, believing that the mind is a
manifestation of the super-soul, or he may be a materialist, and in
either case he may at the same time and with perfect consistency
believe, as a practical scientist, that the mind is a "cause" and has
bodily action as its "effect."

Naturally this point of view offers no difficulties whatever to the
spiritualist. He already looks upon the mind or soul as the "originating
cause" of everything.

[Sidenote: Thoughts Treated as Causes]

But the materialist, too, may in accordance with his speculative theory
continue to insist that _brain-action_ is the "originating cause" of
mental life; yet if the facts show that certain thoughts are invariably
followed by certain bodily activities, the materialist may without
violence to his theories agree to the great practical value of _treating
these thoughts as immediate causes_, no matter what the history of
creation may have been.