Chapter 8, Footnote #02
To render the analysis here given of the possible states of the mind in point of intentionality absolutely complete, it must be pushed to such a farther degree of minuteness, as to some eyes will be apt to appear trifling. On this account it seemed advisable to discard what follows, from the text to a place where any one who thinks proper may pass by it. An act of the body, when of the positive kind, is motion: now in motion there are always three articles to be considered: 1. The quantity of matter that moves: 2. The direction in which it moves: and, 3. The velocity with which it moved. Correspondent to these three articles, are so many modes of intentionality, with regard to an act, considered as being only in its first stage. To be completely unintentional, it must be unintentional with respect to every one of these three particulars. This is the case with those acts which alone are properly termed involuntary: acts, in the performance of which the will has no sort of share: such as the contraction of the heart and arteries.
Upon this principle, acts that are unintentional in their first stage, may be distinguished into such as are completely unintentional, and such as are incompletely unintentional: and these again may be unintentional, either in point of quantity of matter alone, in point of direction alone, in point of velocity alone, or in any two of these points together.
The example given further on may easily be extended to this part of the analysis, by any one who thinks it worth the while.
There seem to be occasions in which even these disquisitions, minute as they may appear, may not be without their use in practice. In the case of homicide, for example, and other corporal injuries, all the distinctions here specified may occur, and in the course of trial may, for some purpose or other, require to be brought to mind, and made the subject of discourse. What may contribute to render the mention of them pardonable, is the use that might possibly be made of them in natural philosophy. In the hands of an expert metaphysician, these, together with the foregoing chapter on human actions, and the section on facts in general, in title Evidence of the Book of Procedure, might, perhaps, be made to contribute something towards an exhaustive analysis of the possible varieties of mechanical inventions.