ideas, and by their juxta-position and comparison. In order, therefore, to judge of these systems, we need only consider, whether it be possible, from reason alone, to distinguish betwixt moral good and evil, or whether there must concur some other principles to enable us to make that distinction.
If morality had naturally no influence on human passions and actions, 'twere in vain to take such pains to inculcate it; and nothing wou'd be more fruitless than that multitude of rules and precepts, with which all moralists abound. Philosophy is commonly divided into speculative and practical; and as morality is always comprehended under the latter division, 'tis supposed to influence our passions and actions, and to go beyond the calm and indolent judgments of the understanding. And this is confirm'd by common experience, which informs us, that men are often govern'd by their duties, and are deter'd from some actions by the opinion of injustice, and impell'd to others by that of obligation.
Since morals, therefore, have an influence on the actions and affections, it follows, that they cannot be deriv'd from reason; and that because reason alone, as we have already prov'd, can never have any such influence. Morals excite passions, and produce or prevent actions. Reason of itself is utterly impotent in this particular. The rules of morality, therefore, are not conclusions of our reason.
No one, I believe, will deny the justness of this inference; nor is there any other means of evading it, than by denying that principle, on which it is founded. As long as it is allow'd, that reason has no influence on our passions and actions, 'tis in vain to pretend, that morality is discover'd only by a deduction of reason. An active principle can never be founded on an inactive; and if reason be inactive in itself, it must remain so in all its shapes and appearances, whether it exerts itself in natural or moral subjects, whether it considers the powers of external bodies, or the actions of rational beings.
It would be tedious to repeat all the arguments, by which
