things desirable. If so, happiness is the sole end of
human action, and the promotion of it the test by which to judge of all
human conduct; from whence it necessarily follows that it must be the
criterion of morality, since a part is included in the whole.

And now to decide whether this is really so; whether mankind do desire
nothing for itself but that which is a pleasure to them, or of which the
absence is a pain; we have evidently arrived at a question of fact and
experience, dependent, like all similar questions, upon evidence. It can
only be determined by practised self-consciousness and self-observation,
assisted by observation of others. I believe that these sources of
evidence, impartially consulted, will declare that desiring a thing and
finding it pleasant, aversion to it and thinking of it as painful, are
phenomena entirely inseparable, or rather two parts of the same
phenomenon; in strictness of language, two different modes of naming the
same psychological fact: that to think of an object as desirable (unless
for the sake of its consequences), and to think of it as pleasant, are
one and the same thing; and that to desire anything, except in
proportion as the idea of it is pleasant, is a physical and metaphysical
impossibility.

So obvious does this appear to me, that I expect it will hardly be
disputed: and the objection made will be, not that desire can possibly
be directed to anything ultimately except pleasure and exemption from
pain, but that the will is a different thing from desire; that a person
of confirmed virtue, or any other person whose purposes are fixed,
carries out his purposes without any thought of the pleasure he has in
contemplating them, or expects to derive from their fulfilment; and
persists in acting on them, even though these pleasures are much
diminished, by changes in his character or decay of his passive
sensibilities, or are outweighed by the pains which the pursuit of the
purposes may bring upon him. All this I fully admit, and have stated it
elsewhere, as positively and emphatically as any one. Will, the active
phenomenon, is a different thing from desire, the state of passive
sensibility, and though originally an offshoot from it, may in time take
root and detach itself from the parent stock; so much so, that in the
case of an habitual purpose, instead of willing the thing because we
desire it, we often desire it only because we will it. This, however, is
but an instance of