The power to imagine things that have not been actually experienced has, on the one hand, commonly been regarded as a key aspect of creative and intelligent thought. On the other hand, this power of imagination has equally commonly been regarded as a rather passive and mechanical capacity to arrange and order the images of thought arising associatively out of memory, with the aid of which the mind may at best make routine sorts of adjustments, and at worst contrive to deceive itself in such a way as may be conducive to its own pleasure, comfort, and superficial satisfaction.