In like manner Thummig, the disciple of Leibnitz, has the following language, as quoted by Sir William Hamilton: “It is to philosophize very crudely concerning mind, and to image everything in a corporeal manner, to conceive that actuating reasons are something external, which make an impression on the mind, and _to distinguish motives from the active principle itself_.” Now this language, it seems, is found in Thummig’s defence of the last paper of Leibnitz (who died before the controversy was terminated) against the answer of Clarke. But, surely, if it is a great mistake, as the author insists it is, to distinguish motives from the active principle itself; then to say that the active principle is determined by motives, is to say that the active principle is determined by itself. And having reached this point, the disciple of Leibnitz finds himself planted precisely on the position he had undertaken to overthrow, namely, that the will is determined by itself. And again, if it be wrong to distinguish the motive from the active principle itself, then to say that the active principle never departs from the motive, is to affirm that a thing is always as itself. The great service which a false psychology has rendered to the cause of necessity is easily seen. For having identified an act of the will with a state of the sensibility, which is universally conceived to be necessitated, the necessitarian is delivered from more than half his labours. By merging a phenomenon or manifestation of the will in a state of the sensibility, it seems to lose its own characteristic, which is incompatible with the scheme of necessity, and to assume the characteristic of feeling, which is perfectly reconcilable with it; nay, which demands the scheme of necessity to account for its existence. Thus, the system of necessity is based on a false psychology, on which it has too securely stood from the earliest times down to the present day. But the stream of knowledge, ever deepening and widening in its course, has been gradually undermining the foundations of this dark system. Section II. The scheme of necessity is directed against a false issue. As we have seen in the last section, the argument of the necessitarian is frequently directed against a false issue; but the point is worthy of a still more careful consideration.