never in _immediate_ contact, without passing through the intermediate
mental links. The question is of theoretic importance with regard to
the way in which the process of "association of ideas" must be
conceived; and Dr. Ebbinghaus' attempt is as successful as it is
original, in bringing two views, which seem at first sight
inaccessible to proof, to a direct practical test, and giving the
victory to one of them. His experiments conclusively show that an idea
is not only "associated" directly with the one that follows it, and
with the rest _through that_, but that it is _directly_ associated
with _all_ that are near it, though in unequal degrees. He first
measured the time needed to impress on the memory certain lists of
syllables, and then the time needed to impress lists of the same
syllables with gaps between them. Thus, representing the syllables by
numbers, if the first list was 1, 2, 3, 4 ... 13, 14, 15, 16, the
second would be 1, 3, 5 ... 15, 2, 4, 6 ... 16, and so forth, with
many variations.

Now, if 1 and 3 in the first list were learned in that order merely by
1 calling up 2, and by 2 calling up 3, leaving out the 2 ought to
leave 1 and 3 with no tie in the mind; and the second list ought to
take as much time in the learning as if the first list had never been
heard of. If, on the other hand, 1 has a _direct_ influence on 3 as
well as on 2, that influence should be exerted even when 2 is dropped
out; and a person familiar with the first list ought to learn the
second one more rapidly than otherwise he could. This latter case is
what actually occurs; and Dr. Ebbinghaus has found that syllables
originally separated by as many as seven intermediaries still reveal,
by the increased rapidity with which they are learned in order, the
strength of the tie that the original learning established between
them, over the heads, so to speak, of all the rest. It may be that