| If he does not answer this challenge, as it is certain he cannot, we may from his silence and our own observation establish our conclusion. |
| Thus we find, that all simple ideas and impressions resemble each other; and as the complex are formed from them, we may affirm in general, that these two species of perception are exactly correspondent. |
| Having discovered this relation, which requires no farther examination, I am curious to find some other of their qualities. |
| Let us consider how they stand with regard to their existence, and which of the impressions and ideas are causes, and which effects. |
| The full examination of this question is the subject of the present treatise; and therefore we shall here content ourselves with establishing one general proposition, THAT ALL OUR SIMPLE IDEAS IN THEIR FIRST APPEARANCE ARE DERIVED FROM SIMPLE IMPRESSIONS, WHICH ARE CORRESPONDENT TO THEM, AND WHICH THEY EXACTLY REPRESENT. |
| In seeking for phenomena to prove this proposition, I find only those of two kinds; but in each kind the phenomena are obvious, numerous, and conclusive. |
| I first make myself certain, by a new, review, of what I have already asserted, that every simple impression is attended with a correspondent idea, and every simple idea with a correspondent impression. |
| From this constant conjunction of resembling perceptions I immediately conclude, that there is a great connexion betwixt our correspondent impressions and ideas, and that the existence of the one has a considerable influence upon that of the other. |
| Such a constant conjunction, in such an infinite number of instances, can never arise from chance; but clearly proves a dependence of the impressions on the ideas, or of the ideas on the impressions. |
| That I may know on which side this dependence lies, I consider the order of their first appearance; and find by constant experience, that the simple impressions always take the precedence of their correspondent ideas, but never appear in the contrary order. |
| To give a child an idea of scarlet or orange, of sweet or bitter, I present the objects, or in other words, convey to him these impressions; but proceed not so absurdly, as to endeavour to produce the impressions by exciting the ideas. |
| Our ideas upon their appearance produce not their correspondent impressions, nor do we perceive any colour, or feel any sensation merely upon thinking of them. |
| On the other hand we find, that any impression either of the mind or body is constantly followed by an idea, which resembles it, and is only different in the degrees of force and liveliness, The constant conjunction of our resembling perceptions, is a convincing proof, that the one are the causes of the other; and this priority of the impressions is an equal proof, that our impressions are the causes of our ideas, not our ideas of our, impressions. |
| To confirm this I consider Another plain and convincing phaenomenon; which is, that, where-ever by any accident the faculties, which give rise to any impressions, are obstructed in their operations, as when one is born blind or deaf; not only the impressions are lost, but also their correspondent ideas; so that there never appear in the mind the least traces of either of them. |
| 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. |
| Suppose therefore a person to have enjoyed his sight for thirty years, and to have become perfectly well acquainted with colours of all kinds, excepting one particular shade of blue, for instance, which it never has been his fortune to meet with. |