new force as it advances; and that our reasonings concerning morals will corroborate whatever has been said concerning the understanding and the passions.  Morality is a subject that interests us above all others:  We fancy the peace of society to be at stake in every decision concerning it; and it is evident, that this concern must make our speculations appear more real and solid, than where the subject is, in a great measure, indifferent to us.  What affects us, we conclude can never be a chimera; and as our passion is engaged on the one side or the other, we naturally think that the question lies within human comprehension; which, in other cases of this nature, we are apt to entertain some doubt of.  Without this advantage I never should have ventured upon a third volume of such abstruse philosophy, in an age, wherein the greatest part of men seem agreed to convert reading into an amusement, and to reject every thing that requires any considerable degree of attention to be comprehended.

It has been observed, that nothing is ever present to the mind but its perceptions; and that all the actions of seeing, hearing, judging, loving, hating, and thinking, fall under this denomination.  The mind can never exert itself in any action, which we may not comprehend under the term of perception; and consequently that term is no less applicable to those judgments, by which we distinguish moral good and evil, than to every other operation of the mind.  To approve of one character, to condemn another, are only so many different perceptions.

Now as perceptions resolve themselves into two kinds, viz. impressions and ideas, this distinction gives rise to a question, with which we shall open up our present enquiry concerning morals.  Whether it is by means of our ideas or impressions we distinguish betwixt vice and virtue, and pronounce an action blameable or praiseworthy?  This will immediately cut off all loose discourses and declamations, and reduce us to something precise and exact on the present subject.

Those who affirm that virtue is nothing but a conformity to reason; that there are eternal fitnesses and unfitnesses of things, which are the same to every rational being that considers them; that the immutable measures of right and wrong impose an obligation, not only on human creatures, but also on the Deity himself:  All these systems concur in the opinion, that morality, like truth, is discerned merely by ideas, and by their juxta-position and comparison.  In order, therefore, to judge of these systems, we need only consider, whether it be possible, from reason alone, to distinguish betwixt moral good and evil, or whether there must concur some other principles to enable us to make that distinction,