The perception no doubt is formed partly by means of the physical eye, partly by the mind, which fills up what is wanting with ideas derived from knowledge and experience, and out of the fragments visible to the physical eye forms a whole; but that this whole should present itself vividly to the reason, should become a picture, a mentally drawn map, that this picture should be fixed, that the details should never again separate themselves--all that can only be effected by the mental faculty which we call imagination.

If some great poet or painter should feel hurt that we require from his goddess such an office; if he shrugs his shoulders at the notion that a sharp gamekeeper must necessarily excel in imagination, we readily grant that we only speak here of imagination in a limited sense, of its service in a really menial capacity.

But, however slight this service, still it must be the work of that natural gift, for if that gift is wanting, it would be difficult to imagine things plainly in all the completeness of the visible.

That a good memory is a great assistance we freely allow, but whether memory is to be considered as an independent faculty of the mind in this case, or whether it is just that power of imagination which here fixes these things better on the memory, we leave undecided, as in many respects it seems difficult upon the whole to conceive these two mental powers apart from each other.
That practice and mental acuteness have much to do with it is not to be denied.

Puysegur, the celebrated Quartermaster-General of the famous Luxemburg, used to say that he had very little confidence in himself in this respect at first, because if he had to fetch the parole from a distance he always lost his way.
It is natural that scope for the exercise of this talent should increase along with rank.