"Day like a mighty river flowing in."

Imagination is not the exclusive appanage of artists, but belongs in
varying degrees to all men. It is simply the power of forming images.
Supplying the energy of Sense where Sense cannot reach, it brings into
distinctness the facts, obscure or occult, which are grouped round an
object or an idea, but which are not actually present to Sense. Thus,
at the aspect of a windmill, the mind forms images of many
characteristic facts relating to it; and the kind of images will depend
very much on the general disposition, or particular mood, of the mind
affected by the object: the painter, the poet, and the moralist will
have different images suggested by the presence of the windmill or its
symbol. There are indeed sluggish minds so incapable of self-evolved
activity, and so dependent on the immediate suggestions of Sense, as to
be almost destitute of the power of forming distinct images beyond the
immediate circle of sensuous associations; and these are rightly named
unimaginative minds; but in all minds of energetic activity, groups and
clusters of images, many of them representing remote relations,
spontaneously present themselves in conjunction with objects or their
symbols. It should, however, be borne in mind that Imagination can only
recall what Sense has previously impressed. No man imagines any detail
of which he has not previously had direct or indirect experience.
Objects as fictitious as mermaids and hippogriffs are made up from the
gatherings of Sense.

"Made up from the gatherings of Sense" is a phrase which may seem to
imply some peculiar plastic power such as is claimed exclusively for
artists: a power not of simple recollection, but of recollection and
recombination. Yet this power belongs also to philosophers. To combine