cultivating reason, being destitute of experience, frequently deceives
himself upon the means of arriving at this end; sometimes the means he
employs are unpleasant to his fellows, because they are prejudicial to
their interests; or else those of which he avails himself appear
irrational, because they remove him from the end to which he would
approximate: but whatever may be these means, they have always
necessarily and invariably for object, either an existing or imaginary
happiness; are directed to preserve himself in a state analogous to his
mode of existence, to his manner of feeling, to his way of thinking;
whether durable or transitory. It is from having mistaken this truth,
that the greater number of moral philosophers have made rather the
romance, than the history of the human heart; they have attributed the
actions of man to fictitious causes; at least they have not sought out
the necessary motives of his conduct. Politicians and legislators have
been in the same state of ignorance; or else impostors have found it
much shorter to employ imaginary motive-powers, than those which really
have existence: they have rather chosen to make man wander out of his
way, to make him tremble under incommodious phantoms, than guide him to
virtue by the direct road to happiness; notwithstanding the conformity
of the latter with the natural desires of his heart. So true it is, that
_error can never possibly be useful, to the human species_.

However this may be, man either sees or believes he sees, much more
distinctly, the necessary relation of effects with their causes in
natural philosophy than in the human heart; at least he sees in the
former sensible causes constantly produce sensible effects, ever the
same, when the circumstances are alike. After this, he hesitates not to
look upon physical effects as necessary, whilst he refuses to
acknowledge necessity in the acts of the human will; these he has,
without any just foundation, attributed to a motive-power that acts