That sounds like David Hume. He says that creativity completely relies on previous experiences. A unicorn for example is simply the idea of a horse with the idea of a centered horn on its head like a rhinocerous. The shape of the horn is simply the idea of a conch shell or something else recollected by the memory.

This definition of creativity seems to be able to explain almost all new ideas. I wonder, however, how the original ideas were conceived. I suppose its possible that they were born from experiences just like anything else.

We know that Tolkien's imagination was so fantastic and vivid but his creatures and settings were not at all new. The world he "created" can be found in bits and pieces from Anglo Saxon and Nordic Mythology.

I suppose Hume's definition can go a long way in helping me understand the world.