There is no Moral rule, that may not have a reason demanded for it; which ought not to be the case with any innate principle.

That we should do as we would be done by, is the foundation of all morality, and yet, if proposed to any one for the first time, might not such an one, without absurdity, ask a reason why?
But this would imply that there is some deeper principle for it to repose upon, capable of being assigned as its motive; that it is not ultimate, and therefore not innate.

That men should observe compacts is a great and undeniable rule, yet, in this, a Christian would give as reason the command of God; a Hobbist would say that the public requires it, and would punish for disobeying it; and an old heathen philosopher would have urged that it was opposed to human virtue and perfection.
Bound up with this consideration, is the circumstance that moral rules differ among men, according to their views of happiness.

The existence of God, and our obedience to him, are manifest in many ways, and are the true ground of morality, seeing that only God can call to account every offender; yet, from the union of virtue and public happiness, all men have recommended the practice of what is for their own obvious advantage.

There is quite enough in this self-interest to cause moral rules to be enforced by men that care neither for the supreme Lawgiver, nor for the Hell ordained by him to punish transgressors.
After all, these great principles of morality are more commended than practised.