Thomas Hobbes, in his seminal philosophical work, Leviathan, proposes the following of human imagination:
"[I]magination being only of those things which have been formerly perceived by sense, either all at once, or by parts at several times[...]"
In doing so, Hobbes raises many interesting questions about our perceptions of the creativity certain humans possess. Phrases like "something nobody has ever thought of before" are endlessly parroted as some claim of grandiosity -- yet little actual thought is given to the truth of the matter. Perhaps, then, it is important that we distinguish between these two primary notions of imagination as proposed by Hobbes: that which we have perceived as a whole, and that which he have perceived in parts.
That which we have perceived as a whole, or whole-based imagination, is oft seen as the "common" form of imagination, and is, all too regularly, lambasted by elitists and artists alike. There may be nothing truly negative about such a form of imagination; mental replication, as it were, is an important function of perception, and no less important than its counterpart in imagination. This distinction was explored through mid-twentieth century Pop Art -- artists like Warhol and Licthenstein were noted for their renderings of the mundane (Warhol most obviously with his Campbell's soup can, Lichtenstein with his renditions of comic art) in a way that is not importantly different than the original, excepting, of course, size. These easily slide into our first form of imagination.
That which we have perceived in parts, or, more easily, part-based imagination, is typically seen as a higher form of imagination, regardless of whether or not this is truly the case. Often, this is mistaken for something it most certainly isn't: the ability to create new works of art. This, however, appears not to be the case. Instead, what appears to be a new production is only a re-structuring in such a way that something not entirely similar to its original parts is produced. Hobbes gives an excellent example of such:
"[Part-based imagination] is compounded, when from the sight of a man at one time, and of a horse at another, we conceive in our mind a centaur."
These two notions of imagination -- not the only two proposed by Hobbes, but certainly the most important, and the only ones of any real depth in this matter -- are not mutually exclusive within a person; rather, they are both necessary in a being possessing any sort of goodness. Unfortunately, one side or the other is constantly rejected, at least outwardly. Take, for example, a man -- a musician, perahps -- who is fond of exercising the part-based imagination, and rather unfond of a whole-based imagination. Following his mental guidelines of imagination, he may avoid thinking of anything "whole" he has perceived, merely on the conception that such will distort his personal creativity. At this point he may come to the opinion that existing in society will not allow him to exercise a part-based imagination when there is a constant influx of wholes. From this, perhaps he will lock himself in a darkened room -- one where he will be free from influence of "new" wholes.
What he fails to recognize, and what this example pushes to the surface, is that Hobbes' distinction of imagination is flawed: it seems that either wholes must be created from nothing, or wholes must be imagined from parts, which seems far more reasonable than assuming something so grand as pure, unenebriated creation from nothingness. If the latter is the case, which it certainly appears to be, one must wonder from where these initial wholes -- those which we extract parts in our perceptions -- came from, if not imagined constructs of parts. Of course, this is essentially a parroting of a problem echoing across philosophy: can something, in fact, come from nothing?
It seems, then, that we can come only to one real conclusion: while Hobbes' notion of forms of imagination may seem, at initial glance, clear, distinct, and certainly unrelated, it is not the case. Upon further investigation, it appears that the two notions of part-based imagination and whole-based imagination are not only interrelated, but each is necessary for the other to exist.