such as the whiteness, hardness, and coldness, of a snow-ball, and can
experience at the same time many irritative ideas of surrounding bodies,
which we do not attend to, as mentioned in Section VII. 3. 2. But those
ideas which belong to the same sense, seem to be more easily combined into
synchronous tribes, than those which were not received by the same sense,
as we can more easily think of the whiteness and figure of a lump of sugar
at the same time, than the whiteness and sweetness of it.

2. As these ideas, or sensual motions, are thus excited with greater or
less degrees of combination; so we have a power, when we repeat them either
by our volition or sensation, to increase or diminish this degree of
combination, that is, to form compounded ideas from those, which were more
simple; and abstract ones from those, which were more complex, when they
were first excited; that is, we can repeat a part or the whole of those
sensual motions, which did constitute our ideas of perception; and the
repetition of which now constitutes our ideas of recollection, or of
imagination.

3. Those ideas, which we repeat without change of the quantity of that
combination, with which we first received them, are called complex ideas,
as when you recollect Westminster Abbey, or the planet Saturn: but it must
be observed, that these complex ideas, thus re-excited by volition,
sensation, or association, are seldom perfect copies of their correspondent
perceptions, except in our dreams, where other external objects do not
detract our attention.

4. Those ideas, which are more complex than the natural objects that first
excited them, have been called compounded ideas, as when we think of a
sphinx, or griffin.