LECTURE  XIX

§ I. Qualitative Change of Ide.as. § II. Association of Ideas ;
Simultaneous Association ; Complication. § III. Assimil.ation.
§ IV. Theory of Simultaneous Associ.i.tion.

§   I

IF we look for a moment at the coming and going of ideas in
our minds, we cannot fail to see that the plot of the play
is determined by two influences,—accidental external sense-
impressions and previous experiences. Which of the two pre¬
ponderates at a particular time depends upon circumstances.
Cast your eye over a landscape, or follow attentively the render¬
ing of a musical composition, and you will find yourselves
seemingly wholly given up to the external impressions ; subjec¬
tive tendencies coming in only secondarily, and rather as feelings
than as ideas. Now try to recall the events of the past few days.
External sense-impressions are hardly noticed ; and the train
of ideas, so far as it is clear and distinct, consists solely of
reproductions of previous mental experiences. These are both
extreme cases ; ordinarily we find ourselves in some intermediate
frame of mind. Memory-ideas are aroused by sense-perceptions,
and again interrupted by new impressions. Wherever the in¬
fluence of past experience is traceable, we find the memory-
ideas aroused evidencing a definite relation to the condition
of consciousness at the time. Sense-perception varies with
every variation of the environment; but the memory-image is
always suggested, whether by a sense-perception or a previous
memory-image You will object that now and again a recollection
crops up suddenly and for no apparent reason. But attentive
introspection will in most of these cases enable you to discover
the thread of connection with your present state of mind.
However little obvious  this  connection,  then, we may safely