I should like to begin with a few remarks about the history of Gestalt
psychology--because not all chapters of this history are generally
known. In the eighties of the past century, psychologists in Europe were
greatly disturbed by von Ehrenfels' claim that thousands of percepts
have characteristics which cannot be derived from the characteristics of
their ultimate components, the so-called sensations. Chords and melo-
dies in hearing, the shape characteristics of visual objects, the rough-
ness or the smoothness of tactual impressions, and so forth, were used
as examples. All these "Gestalt qualities" have one thing in common.
When the physical stimuli in question are considerably changed, while
their relations are kept constant, the Gestalt qualities remain about the
same. But, at the time, it was generally assumed that the sensations in-
volved are individually determined by their individual stimuli and must
therefore change when these are greatly changed. How, then, could any
characteristics of the perceptual situation remain constant under these
conditions? Where did the Gestalt qualities come from? Ehrenfels'
qualities are not fancy ingredients of this or that particular situation
which we might safely ignore. Both positive and negative aesthetic
characteristics of the world around us, not only of ornaments, paintings,
sculptures, tunes, and so forth, but also of trees, landscapes, houses,
cars--and other persons--belong to this class. That relations between
the sexes largely depend on specimens of the same class needs hardly
be emphasized. It is, therefore, not safe to deal with problems of psy-
chology as though there were no such qualities. And yet, beginning
with Ehrenfels himself, psychologists have not been able to explain
their nature.

This holds also for the men who were later called Gestalt psycholo-
gists, including the present speaker. Wertheimer's ideas and investiga-
tions developed in a different direction. His thinking was also more radi-
cal than that of Ehrenfels. He did not ask: How are Gestalt qualities
possible when, basically, the perceptual scene consists of separate ele-
ments? Rather, he objected to this premise, the thesis that the psycholo-
gist's thinking must begin with a consideration of such elements. From
a subjective point of view, he felt, it may be tempting to assume that all
perceptual situations consist of independent, very small components.
For, on this assumption, we obtain a maximally clear picture of what
lies behind the observed facts. But, how do we know that a subjective
clarity of this kind agrees with the nature of what we have before us?
Perhaps we pay for the subjective clearness of the customary picture
by ignoring all processes, all functional interrelations, which may have

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