onslaught on "abstract ideas." They
meant by an idea approximately what we should call an image. Locke
having maintained that he could form an idea of triangle in general,
without deciding what sort of triangle it was to be, Berkeley contended
that this was impossible. He says:

"Whether others, have this wonderful faculty of abstracting their ideas,
they best can tell: for myself, I dare be confident I have it not. I
find, indeed, I have indeed a faculty of imagining, or representing to
myself, the ideas of those particular things I have perceived, and of
variously compounding and dividing them. I can imagine a man with two
heads, or the upper parts of a man joined to the body of a horse. I
can consider the hand, the eye, the nose, each by itself abstracted or
separated from the rest of the body. But, then, whatever hand or eye
I imagine, it must have some particular shape and colour. Likewise the
idea of a man that I frame to myself must be either of a white, or a
black, or a tawny, a straight, or a crooked, a tall, or a low, or
a middle-sized man. I cannot by any effort of thought conceive the
abstract idea above described. And it is equally impossible for me to
form the abstract idea of motion distinct from the body moving, and
which is neither swift nor slow, curvilinear nor rectilinear; and the
like may be said of all other abstract general ideas whatsoever. To be
plain, I own myself able to abstract in one sense, as when I consider
some particular parts of qualities separated from others, with which,
though they are united in some object, yet it is possible they may
really exist without them. But I deny that I can abstract from one
another, or conceive separately, those qualities which it is impossible
should exist so separated; or that I can frame a general notion, by
abstracting from particulars in the manner aforesaid--which last are
the two proper acceptations of ABSTRACTION. And there is ground to think
most men will acknowledge themselves to be in my case. The generality of
men which are simple and illiterate never pretend to ABSTRACT NOTIONS.
It is said they are difficult and not to be attained without pains and
study; we may therefore reasonably conclude that, if such there be, they
are confined only to the learned.

"I proceed to examine what can be alleged in defence of the doctrine of
abstraction, and try if I can discover what it is that inclines the men
of speculation to embrace an opinion so remot