put it
past doubt with me, that they have perception, and retain ideas in their
memories, and use them for patterns. For it seems to me impossible that
they should endeavour to conform their voices to notes (as it is plain
they do) of which they had no ideas. For, though I should grant sound
may mechanically cause a certain motion of the animal spirits in the
brains of those birds, whilst the tune is actually playing; and that
motion may be continued on to the muscles of the wings, and so the bird
mechanically be driven away by certain noises, because this may tend to
the bird's preservation; yet that can never be supposed a reason why it
should cause mechanically--either whilst the tune is playing, much less
after it has ceased--such a motion of the organs in the bird's voice as
should conform it to the notes of a foreign sound, which imitation can
be of no use to the bird's preservation. But, which is more, it cannot
with any appearance of reason be supposed (much less proved) that birds,
without sense and memory, can approach their notes nearer and nearer by
degrees to a tune played yesterday; which if they have no idea of in
their memory, is now nowhere, nor can be a pattern for them to imitate,
or which any repeated essays can bring them nearer to. Since there is
no reason why the sound of a pipe should leave traces in their brains,
which, not at first, but by their after-endeavours, should produce the
like sounds; and why the sounds they make themselves, should not make
traces which they should follow, as well as those of the pipe, is
impossible to conceive.

CHAPTER XI.

OF DISCERNING, AND OTHER OPERATIONS OF THE MIND.

1. No Knowledge without Discernment.

Another faculty we may take notice of in our minds is that of DISCERNING
and DISTINGUISHING between the several ideas it has. It is not enough to
have a confused perception of something in general. Unless the mind had
a distinct perception of different objects and their qualities, it would
be capable of very little knowledge, though the bodies that affect us
were as busy about us as they are now, and the; mind were continually
employed in thinking. On this faculty of distinguishing one thing
from another depends the evidence and certainty of several, even very
general, propositions, which have passed for innate truths;--because
men, overlooking the true cause why those propositions find universal
assent, impute it wholly to native uniform impressi