Let us now suppose a violent death; that for example, of a man whose head is carried off by a cannon-ball. Can the pain he suffers last longer than a moment? Has he, in the interval of that moment, a succession of ideas so rapid, that he can imagine the pangs he feels are equal to an hour, a day, an age? These points we shall endeavour to discuss.
I own the succession of our ideas is, in reality, the only natural measure of time; and that, in proportion as they flow with more or less uniformity, they appear of longer or shorter duration. But in this measure there is an unit, or fixed point, which is neither arbitrary nor indefinite, but determined by Nature, and correspondent to our organization. Between two ideas which succeed each other, there must be an interval that separates them; however quick one thought may be, a little time is required before it can be followed by another, no succession being possible in an indivisible instant. The same observation holds with respect to the sensations of the body. A transition from pain to pleasure, or even from one pain to another, requires a certain interval. This interval, by which our thoughts and sensations are necessarily separated, is the unit I mention; and it can neither be extremely long, nor extremely short; it must even be nearly upon an equality in its duration, as it depends upon the nature of the mind, and the organization of the body, whose movements can have but one certain degree of celerity. In the same individual, therefore, there can be no succession of ideas so rapid, or so slow, as to produce that enormous difference of duration, by which the pain of a minute is converted into that of an hour, a day, or a century.
A very acute pain, of however short continuance, tends to produce either a swoon, or death. As our organs have only a certain degree of strength, they cannot resist above a certain degree of pain. If that becomes excessive, it ceases, because the body being incapable of supporting it, is still less capable to transmit it to the mind, with which it can hold no correspondence, but by the action of these organs. Here this action ceases, and therefore, all internal sensation must necessarily cease also.