Locke regarded his _Human Understanding_ as the preliminary to an ethical enquiry; and Hume seems to have considered his _Principles of Morals_ the most vital of his works.

It may be true, as the mordant insight of Mark Pattison suggested, that "those periods in which morals have been represented as the proper study of man, and his only business, have been periods of spiritual abasement and poverty." Certainly no one will be inclined to claim for the eighteenth century the spiritual idealism of the seventeenth, though Law and Bishop Wilson and the Wesleyan revival will make us generalize with caution.

But the truth was that theological ethics had become empty and inadequate, and the problem was therefore urgent.

That is why Shaftesbury, Hutcheson, Hume and Adam Smith--to take only men of the first eminence--were thinking not less for politics than for ethics when they sought to justify the ways of man to man.

For all of them saw that a theory of society is impossible without the provision of psychological foundations; and those must, above all, result in a theory of conduct if the social bond is to be maintained.