tion to take place in a lesser Degree. A Man of mild Manners can form no Notion of inveterate Revenge or Cruelty; nor can a selfish Heart easily conceive the Heights of Friendship and Generosity. 'Tis readily allow'd, that other Beings may possess many Senses, of which we can have no Conception; because the Ideas of them have never been introduc'd to us in the only Manner, by which an Idea can have access to the Mind, viz. by the actual Feeling and Sensation.
There is, however, one contradictory Phænomenon, which may prove, that 'tis not absolutely impossible for Ideas to go before their correspondent Impressions. I believe it will readily be allow'd, that the several distinct Ideas of Colours, which enter by the Eyes, or those of Sounds, which are convey'd by the Hearing, are really different from each other; tho', at the same time, resembling. Now if this be true of different Colours, it must be no less so, of the different Shades of the same Colour; and each Shade produces a distinct Idea, independent of the rest. For if this should be deny'd, 'tis possible, by the continual Gradation of Shades, to run a Colour insensibly into what is most remote from it; and if you will not allow any of the Means to be different, you cannot, without Absurdity, deny the Extremes to be the same. Suppose, therefore, a Person to have enjoy'd his Sight for thirty Years, and to have become perfectly wellacquainted
