point or circumstance of resemblance shoud be distinct or separable from
that in which they differ. BLUE and GREEN are different simple ideas, but
are more resembling than BLUE and SCARLET; tho their perfect simplicity
excludes all possibility of separation or distinction. It is the same case
with particular sounds, and tastes and smells. These admit of infinite
resemblances upon the general appearance and comparison, without having
any common circumstance the same. And of this we may be certain, even
from the very abstract terms SIMPLE IDEA. They comprehend all simple
ideas under them. These resemble each other in their simplicity. And yet
from their very nature, which excludes all composition, this
circumstance, In which they resemble, Is not distinguishable nor
separable from the rest. It is the same case with all the degrees In any
quality. They are all resembling and yet the quality, In any individual,
Is not distinct from the degree.]

For this is one of the most extraordinary circumstances in the present
affair, that after the mind has produced an individual idea, upon which
we reason, the attendant custom, revived by the general or abstract term,
readily suggests any other individual, if by chance we form any
reasoning, that agrees not with it. Thus should we mention the word
triangle, and form the idea of a particular equilateral one to correspond
to it, and should we afterwards assert, that the three angles of a
triangle are equal to each other, the other individuals of a scalenum and
isosceles, which we overlooked at first, immediately crowd in upon us,
and make us perceive the falshood of this proposition, though it be true
with relation to that idea, which we had formed. If the mind suggests not
always these ideas upon occasion, it proceeds from some imperfection in
its faculties; and such a one as is often the source of false reasoning
and sophistry. But this is principally the case with those ideas which
are abstruse and compounded. On other occasions the custom is more