pleasing recollection or resentment, which recurs with every recurrency of the idea of the object, or of the associated ones. This recollection keeps up the love or hatred. In like manner the five grateful passions, love, desire, hope, joy, and pleasing recollection, all enhance one another; as do the five ungrateful ones, hatred, aversion, fear, grief, and displeasing recollection. And the whole ten, taken together, comprehend, as appears to me, all the general passions of human nature.
Section IV
OF MEMORY.
Memory was defined in the introduction to be that faculty by which traces of sensations and ideas recur, or are recalled, in the same order and proportion, accurately or nearly, as they were once presented.
Now here we may observe,
First, That memory depends entirely or chiefly on the state of the brain. For diseases, concussions of the brain, spirituous liquors, and some poisons, impair or destroy it; and it generally returns again with the return of health, from the use of proper medicines and methods. And all this is peculiarly suitable to the notion of vibrations. If sensations and ideas arise from peculiar vibrations, and dispositions to vibrate, in the medullary substance of the brain, it is easy to conceive, that the causes above alleged may so confound the sensations and ideas, as that the usual order and proportion of the idea shall be destroyed.
Secondly, The rudiments of memory are laid in the perpetual recurrency of the same impressions, and clusters of impressions. How these leave traces, in which the order is preserved, may be understood from the eighth, ninth, tenth, and eleventh propositions.
The traces which letters, and words, i.e. clusters of letters, leave, afford an instance and example of this. And, as in languages the letters are fewer than the syllables, the syllables than the words, and the words than the sentences, so the single sensible impressions, and the small clusters of them, are comparatively few in respect of the large clusters; and, being so, they must recur more frequently, so as the sooner to beget those traces which I call the rudiments or elements of memory. When these traces or ideas begin to recur frequently, this also con-
