Part 4 — APHORISMS.—NO. XV.

'Men,' saith my Lord Bacon, 'think to govern words by their own reason: but it also happens that words throw back their force upon the understanding;' and thus, we may justly add, often distort our thoughts, and lead us to very erroneous conclusions.

This is apparently the case with the word motive, in speaking of human volitions. A motive power in mechanics is one that produces motion; and hence the application of the word to the occasion or reason of any particular act of choice, with the all but inevitable fallacy of confounding the idea of a mechanical force with that of an influence upon the mind. That there is some analogy must be admitted; but that there is such similarity as is often assumed, we are obliged to deny. The almost total difference between a mechanical power and a thought or desire—between a material and spiritual subject of operation—is too apt to be left out of the account.