back of the one, and the gibbosity on the back of the other. What noise is
that in the street?--Some horses trotting over the pavement. Here my idea
of the horses includes principally the shape and motion of their legs. So
also the abstract ideas of goodness and courage are still more imperfect
representations of the objects they were received from; for here we
abstract the material parts, and recollect only the qualities.

Thus we abstract so much from some of our complex ideas, that at length it
becomes difficult to determine of what perception they partake; and in many
instances our idea seems to be no other than of the sound or letters of the
word, that stands for the collective tribe, of which we are said to have an
abstracted idea, as noun, verb, chimæra, apparition.

6. Ideas have been divided into those of perception and those of
reflection, but as whatever is perceived must be external to the organ that
perceives it, all our ideas must originally be ideas of perception.

7. Others have divided our ideas into those of memory, and those of
imagination; they have said that a recollection of ideas in the order they
were received constitutes memory, and without that order imagination; but
all the ideas of imagination, excepting the few that are termed simple
ideas, are parts of trains or tribes in the order they were received; as if
I think of a sphinx, or a griffin, the fair face, bosom, wings, claws,
tail, are all complex ideas in the order they were received: and it behoves
the writers, who adhere to this definition, to determine, how small the
trains must be, that shall be called imagination; and how great those, that
shall be called memory.

Others have thought that the ideas of memory have a greater vivacity than
those of imagination: but the ideas of a person in sleep, or in a waking