But, though this distinction betwixt voluntary and involuntary, be not sufficient to justify the distinction betwixt natural abilities and moral virtues, yet the former distinction will afford us a plausible reason, why moralists have invented the latter. Men have observed, that, though natural abilities and moral qualities be in the main on the same footing, there is, however, this difference betwixt them, that the former are almost invariable by any art or industry; while the latter, or at least the actions that proceed from them, may be changed by the motives of rewards and punishment, praise and blame. Hence legislators and divines and moralists have principally applied themselves to the regulating these voluntary actions, and have endeavoured to produce additional motives for being virtuous in that particular. They knew, that to punish a man for folly, or exhort him to be prudent and sagacious, would have but little effect; though the same punishments and exhortations, with regard to justice and injustice, might have a considerable influence. But as men, in common life and conversation, do not carry those ends in view, but naturally praise or blame whatever pleases or displeases them, they do not seem much to regard this distinction, but consider prudence under the character of virtue as well as benevolence, and penetration as well as justice. Nay, we find that all moralists, whose judgment is not perverted by a strict adherence to a system, enter into the same way of thinking; and that the ancient moralists, in particular, made no scruple of placing prudence at the head of the cardinal virtues. There is a sentiment of esteem and approbation, which may be excited, in some degree, by any faculty of the mind, in its perfect state and condition; and to account for this sentiment is the business of _philosophers_. It belongs to _grammarians_ to examine what qualities are entitled to the denomination of _virtue_; nor will they find, upon trial, that this is so easy a task as at first sight they may be apt to imagine. The principal reason why natural abilities are esteemed, is because of their tendency to be useful to the person who is possessed of them. 'Tis impossible to execute any design with success, where it is not conducted with prudence and discretion; nor will the goodness of our intentions alone suffice to procure us a happy issue to our enterprises. Men are superior to beasts principally by the superiority of their reason; and they are the degrees of the same faculty, which set such an infinite difference betwixt one man and another. All the advantages of art are owing to human reason; and where fortune is not very capricious, the most considerable part of these advantages must fall to the share of the prudent and sagacious.