| When we remember any past event, the idea of it flows in upon the mind in a forcible manner; whereas in the imagination the perception is faint and languid, and cannot without difficulty be preserved by the mind steddy and uniform for any considerable time. |
| Here then is a sensible difference betwixt one species of ideas and another. |
| But of this more fully hereafter.[Part II, SECT. 5.] |
| There is another difference betwixt these two kinds of ideas, which:-s no less evident, namely that though neither the ideas, of the memory nor imagination, neither the lively nor faint ideas can make their appearance in the mind, unless their correspondent impressions have gone before to prepare the way for them, yet the imagination is not restrained to the same order and form with the original impressions; while the memory is in a manner tied down in that respect, without any power of variation. |
| It is evident, that the memory preserves the original form, in which its objects were presented, and that where-ever we depart from it in recollecting any thing, it proceeds from some defect or imperfection in that faculty. |
| An historian may, perhaps, for the more convenient Carrying on of his narration, relate an event before another, to which it was in fact posterior; but then he takes notice of this disorder, if he be exact; and by that means replaces the idea in its due position. |
| It is the same case in our recollection of those places and persons, with which we were formerly acquainted. |
| The chief exercise of the memory is not to preserve the simple ideas, but their order and position. |
| In short, this principle is supported by such a number of common and vulgar phaenomena, that we may spare ourselves the trouble of insisting on it any farther. |
| The same evidence follows us in our second principle, OF THE LIBERTY OF THE IMAGINATION TO TRANSPOSE AND CHANGE ITS IDEAS. |
| The fables we meet with in poems and romances put this entirely out of the question. |
| Nature there is totally confounded, and nothing mentioned but winged horses, fiery dragons, and monstrous giants. |
| Nor will this liberty of the fancy appear strange, when we consider, that all our ideas are copyed from our impressions, and that there are not any two impressions which are perfectly inseparable. |
| Not to mention, that this is an evident consequence of the division of ideas into simple and complex. |
| Where-ever the imagination perceives a difference among ideas, it can easily produce a separation. |
| SECT. IV. OF THE CONNEXION OR ASSOCIATION OF IDEAS. |
| As all simple ideas may be separated by the imagination, and may be united again in what form it pleases, nothing would be more unaccountable than the operations of that faculty, were it not guided by some universal principles, which render it, in some measure, uniform with itself in all times and places. |
| Were ideas entirely loose and unconnected, chance alone would join them; and it is impossible the same simple ideas should fall regularly into complex ones (as they Commonly do) without some bond of union among them, some associating quality, by which one idea naturally introduces another. |
| This uniting principle among ideas is not to be considered as an inseparable connexion; for that has been already excluded from the imagination: Nor yet are we to conclude, that without it the mind cannot join two ideas; for nothing is more free than that faculty: but we are only to regard it as a gentle force, which commonly prevails, and is the cause why, among other things, languages so nearly correspond to each other; nature in a manner pointing out to every one those simple ideas, which are most proper to be united in a complex one. |
| The qualities, from which this association arises, and by which the mind is after this manner conveyed from one idea to another, are three, viz. |
| RESEMBLANCE, CONTIGUITY in time or place, and CAUSE and EFFECT. |