In old times, if you asked a person to explain why he came to be remembering at that moment some particular incident in his previous life, the only reply he could make was that his soul is endowed with a faculty called memory; that it is the inalienable function of this faculty to recollect; and that, therefore, he necessarily at that moment must have a cognition of that portion of the past.  This explanation by a ‘faculty’ is one thing which explanation by association has superseded altogether.  If, by saying we have a faculty of memory, you mean nothing more than the fact that we can remember, nothing more than an abstract name for our power inwardly to recall the past, there is no harm done:  we do have the faculty; for we unquestionably have such a power.  But if, by faculty, you mean a principle of explanation of our general power to recall, your psychology is empty.  The associationist psychology, on the other hand, gives an explanation of each particular fact of recollection; and, in so doing, it also gives an explanation of the general faculty.  The ‘faculty’ of memory is thus no real or ultimate explanation; for it is itself explained as a result of the association of ideas.

Nothing is easier than to show you just what I mean by this.  Suppose I am silent for a moment, and then say in commanding accents:  “Remember!  Recollect!” Does your faculty of memory obey the order, and reproduce any definite image from your past?  Certainly not.  It stands staring into vacancy, and asking, “What kind of a thing do you wish me to remember?” It needs in short, a cue.  But, if I say, remember the date of your birth, or remember what you had for breakfast, or remember the succession of notes in the musical scale; then your faculty of memory immediately produces the required result:  the ’cue’ determines its vast set of potentialities toward a particular point.  And if you now look to see how this happens, you immediately perceive that the cue is something contiguously associated with the thing recalled.  The words, ‘date of my birth,’ have an ingrained association with a particular number, month, and year; the words, ‘breakfast this morning,’ cut off all other lines of recall except those which lead to coffee and bacon and eggs; the words, ‘musical scale,’ are inveterate mental neighbors of do, re, mi, fa, sol, la, etc.  The laws of association govern, in fact, all the trains of our thinking which are not interrupted by sensations breaking on us from without.  Whatever appears in the mind must be introduced; and, when introduced, it is as the associate of something already there.  This is as true of what you are recollecting as it is of everything else you think of.