An Enquiry Concerning The Principles Of Morals - pg. 105

This deduction of morals from self-love, or a regard to private interest, is an obvious thought, and has not arisen wholly from the wanton sallies and sportive assaults of the sceptics. To mention no others, POLYBIUS, one of the gravest and most judicious, as well as most moral writers of antiquity, has assigned this selfish origin to all our sentiments of virtue. But though the solid, practical sense of that author, and his aversion to all vain subtilties, render his authority on the present subject very considerable; yet is not this an affair to be decided by authority, and the voice of nature and experience seems plainly to oppose the selfish theory.