THE QUESTION IS ASKED: "Is it true that humans can never imagine things they have never seen before?"
This is not true at all. At the moment I'm imagining a huge, motionlessly swaying uncannily curved form, of impossible color like smooth soapstone corrupted by deep streaks of impurities, its opaque surface lit from within, towering in a hideous majesty over the bleak grey and whitecapped Irish Sea; its wavy tendrils, studded with darkly luminous gem-like buds, extending airily across the pale white sky in measureless, weightless plaits from a central flanged and crenellated structure which resembles nothing, so much as some unholy (or aholy) ten-dimensional cathedral. From round the collar of that structure's foundation by a huge, hempen rope hangs a huger, rudely-lettered and brutally askew cryptic sign: NEO-CTHULHU.
It goes without saying that I've never even seen the Irish Sea.
We can imagine many, many things we've never seen. A veritable and unverifiable host, whose transmission is easily viral for any notion, nonesuch or factoid whose attraction proves subjectively vivid or grabby. The imagination is a fecund breeding ground for all manner of chimeras and phantasms, grown from the spliced genomes and memomes of what all of us together have seen; imagined; described truly, fictitiously, factitiously or outright falsely; or extrapolated wildly or rigorously from there. We can imagine so much more than only what we've seen.
We can imagine its opposite. A thing can have as many opposites as we can plot angles of relation.
We can imagine its complement.
We can imagine its perfection - and there are as many perfections as there can be purposes.
We can imagine its negative image.
We can imagine its composite - its attributes smashed together with those of any other thing or things, in ordered or chaotic fashion!
Now you can say “that's all just combination.” But there are things one human mind can conceive that are so new and so gigantically unprecedented in effect that they could threaten or unhinge the sanity of another. Things that by any sensible use of the words, no one has yet seen. And if out in the universe, there exist unimaginably alien beings, chances are very, supersymmetrically strong that all they are and all they have to show will also be combination. Very likely of the same three fundamental forces (strong, electroweak, gravity) and the same fundamental interactions between them manifesting matter, energy, and if we're all very good, cake.
Creativity is the faculty that takes what's there and makes what you will of it. Imagination is the will at play. Originality is a novel amalgam.
Reality has only the limits we discover. Imagination…has not even those. Do you know what we have not seen?
I do. I know of a great many such whats, and I can imagine a fair few more.
We have not seen Angels. But I can imagine at least eighteen of them.