If we have really no idea of a power or efficacy in any object, or of any real connexion betwixt causes and effects, it will be to little purpose to prove, that an efficacy is necessary in all operations.

We do not understand our own meaning in talking so, but ignorantly confound ideas, which are entirely distinct from each other.

I am, indeed, ready to allow, that there may be several qualities both in material and immaterial objects, with which we are utterly unacquainted; and if we please to call these POWER or EFFICACY, it will be of little consequence to the world.

But when, instead of meaning these unknown qualities, we make the terms of power and efficacy signify something, of which we have a clear idea, and which is incompatible with those objects, to which we apply it, obscurity and error begin then to take place, and we are led astray by a false philosophy.

This is the case, when we transfer the determination of the thought to external objects, and suppose any real intelligible connexion betwixt them; that being a quality, which can only belong to the mind that considers them.
As to what may be said, that the operations of nature are independent of our thought and reasoning, I allow it; and accordingly have observed, that objects bear to each other the relations of contiguity and succession: that like objects may be observed in several instances to have like relations; and that all this is independent of, and antecedent to the operations of the understanding.