Thus the course of the argument leads us to conclude that, since vice and virtue are not discoverable merely by reason, or the comparison of ideas, it must be by means of some impression or sentiment they occasion, that we are able to mark the difference betwixt them. ... Morality, therefore, is more properly felt than judg'd of; tho' this feeling or sentiment is commonly so soft and gentle, that we are apt to confound it with an idea, according to our common custom of taking all things for the same, which have any near resemblance to each other.
An action, or sentiment, or character is virtuous or vicious; why? because its view causes a pleasure or uneasiness of a particular kind. In giving a reason, therefore, for the pleasure or uneasiness, we sufficiently explain the vice or virtue. To have the sense of virtue, is nothing but to feel a satisfaction of a particular kind from the contemplation of a character. The feeling constitutes our praise or admiration. We go no farther; nor do we enquire into the cause of the satisfaction. We do not infer a character to be virtuous, because it pleases: But in feeling that it pleases after such a particular manner, we in effect feel that it is virtuous. The case is the same as in our judgments concerning all kinds of beauty, and tastes, and sensations. Our approbation is imply'd in the immediate pleasure they convey to us.
Hume's view of morality as deriving from an interior "moral sense" places the seat of moral judgment in a relation of analogy with aesthetic taste. This taste in turn, relates to the external senses, by a metaphorical argument indicated in the selection from Hume's "Of the Standard of Taste" listed under "taste."
The different orders of intensity assigned to ideas and feelings, indicated in the first paragraph above, are also of interest. The two kinds of experience are comparable, but mental phenomena are "soft[er]" and more "gentle."