Nor is this only true, where the organs of sensation are entirely destroyed, but likewise where they have never been put in action to produce a particular impression.

We cannot form to ourselves a just idea of the taste of a pine apple, without having actually tasted it.
There is however one contradictory phaenomenon, which may prove, that it is not absolutely impossible for ideas to go before their correspondent impressions.

I believe it will readily be allowed that the several distinct ideas of colours, which enter by the eyes, or those of sounds, which are conveyed by the hearing, are really different from each other, though 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, that each of them produces a distinct idea, independent of the rest.

For if this should be denied, it is 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.