This faculty of laying up and retaining the ideas that are brought into the mind, several other animals seem to have to a great degree, as well as man.  For, to pass by other instances, birds learning of tunes, and the endeavours one may observe in them to hit the notes right, 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 impressions; whereas it in truth depends upon this clear discerning faculty of the mind, whereby it perceives two ideas to be the same, or different.  But of this more hereafter.