The practical scientist ascribes all sorts of qualities to electricity and lays down many laws concerning it without having the remotest idea as to what, in the last analysis, electricity may actually be. He is not concerned with ultimate truths. He does his work, and necessarily so, upon the principle that for all practical purposes he is justified in using any given assumption as a working hypothesis if everything happens just as if it were true.
The practical scientist applies the term "cause" to any object or event that is the invariable predecessor of some other object or event.
For him a "cause" is simply any object or event that may be looked upon as forecasting the action of some other object or the occurrence of some other event.
The point with him is simply this, Does or does not this object or this event in any way affect that object or that event or determine its behavior?
No matter where you look you will find that every fact in Nature is relatively cause and effect according to the point of view. Thus, if a railroad engine backs into a train of cars it transmits a certain amount of motion to the first car. This imparted motion is again passed on to the next car, and so on. The motion of the first car is, on the one 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.
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.