"In the same year [1752] was published at London my _Inquiry Concerning the Principles of Morals_; which in my own opinion (who ought not to judge on that subject) is of all my writings, historical, philosophical, and literary, incomparably the best. It came unnoticed and unobserved into the world." It may commonly be noticed that the relative value which an author ascribes to his own works rarely agrees with the estimate formed of them by his readers; who criticise the products, without either the power or the wish to take into account the pains which they may have cost the producer. Moreover, the clear and dispassionate common sense of the _Inquiry concerning the Principles of Morals_ may have tasted flat after the highly-seasoned _Inquiry concerning the Human Understanding_. Whether the public like to be deceived, or not, may be open to question; but it is beyond a doubt that they love to be shocked in a pleasant and mannerly way. Now Hume's speculations on moral questions are not so remote from those of respectable professors, like Hutcheson, or saintly prelates, such as Butler, as to present any striking novelty. And they support the cause of righteousness in a cool, reasonable, indeed slightly patronising fashion, eminently in harmony with the mind of the eighteenth century; which admired virtue very much, if she would only avoid the rigour which the age called fanaticism, and the fervour which it called enthusiasm. Having applied the ordinary methods of scientific inquiry to the intellectual phenomena of the mind, it was natural that Hume should extend the same mode of investigation to its moral phenomena; and, in the true spirit of a natural philosopher, he commences by selecting a group of those states of consciousness with which every one's personal experience must have made him familiar: in the expectation that the discovery of the sources of moral approbation and disapprobation, in this comparatively easy case, may furnish the means of detecting them where they are more recondite.