undoubtedly be as fruitful and as indispensable as the other.

Dr. Ebbinghaus[1] makes an original addition to heroic psychological
literature in the little work whose title we have given. For more than
two years he has apparently spent a considerable time each day in
committing to memory sets of meaningless syllables, and trying to
trace numerically the laws according to which they were retained or
forgotten. Most of his results, we are sorry to say, add nothing to
our gross experience of the matter. Here, as in the case of the
saints, heroism seems to be its own reward. But the incidental results
are usually the most pregnant in this department; and two of those
which Dr. Ebbinghaus has reached seems to us to amply justify his
pains. The first is, that, in _forgetting_ such things as these lists
of syllables, the loss goes on very much more rapidly at first than
later on. He measured the loss by the number of seconds required to
_relearn_ the list after it had been once learned. Roughly speaking,
if it took a thousand seconds to learn the list, and five hundred to
relearn it, the loss between the two learnings would have been
one-half. Measured in this way, full half of the forgetting seems to
occur within the first half-hour, while only four-fifths is forgotten
at the end of a month. The nature of this result might have been
anticipated, but hardly its numerical proportions.

[Footnote 1: "Ueber das Gedächtniss. Untersuchungen zur
experimentellen Psychologie." Von Herm.
Ebbinghaus. Leipzig: Duncker u. Humblot, 1885. 10+169 pp. 8vo.]

The other important result relates to the question whether ideas are
recalled only by those that previously came immediately before them,
or whether an idea can possibly recall another idea, with which it was