There are of course many books on the imagination. Psychological studies, motivational works, instructions in visualization, research into creativity, guides to using imagination in business, relationships, and self-improvement – these are some of the results that come from a quick internet search on the subject. There are many more. Most definitions of imagination speak of its contrast with reality. My Oxford Dictionary tells me that imagination is the ‘mental faculty of forming images or concepts of objects or situations not existent or not directly experienced.’ Merriam-Webster tells me it is ‘the ability to imagine things that are not real’ – which seems something of a tautology – and ‘something that only exists or happens in your mind.’ The Cambridge Dictionary says that imagination is ‘the ability to form pictures in the mind’ and that it concerns ‘something that you think exists or is true, although in fact is not real or true’. Imagination is of course also creative. Roget’s Thesaurus calls it the ‘power to create in one’s mind,’ and samples of the synonyms it provides range from ‘artistry,’ ‘awareness,’ and ‘inspiration’, to ‘ingenuity,’ ‘insight’ and ‘creativity’.
I believe imagination is one of those things which we all know immediately but which, as I’ve said, we would find difficult to define. Indeed, an exact definition of it would only make it more obscure. Nevertheless, here I will offer my own definition of imagination. It is not necessarily exclusive of others; I give it to emphasize what I take to be imagination’s central work, and also to make clear how it is a different way of understanding the imagination. I take it from the writer Colin Wilson. Imagination, he said, is ‘the ability to grasp realities that are not immediately present’. Not an escape from reality, or a substitute for it, but a deeper engagement with it. We could also say that imagination is simply our ability to grasp reality, or even, in some strange way, to create it, or at least to collaborate in its creation; with whom or what we will look at further on. For the moment let us limit ourselves to the first formulation.
It is because we need imagination to grasp reality – that part of it immediately before us, and its wider horizons that exceed the reach of our physical senses – that we can speak of a ‘knowledge’ of the imagination. Imagination has a noetic character; it is the source and medium of our other way of knowing. It shows us aspects and dimensions of reality that we would miss without it – and which much, if not most of official western culture has missed since the new way of knowing became dominant. While it can be used for fantasy, illusion, make-believe, and escapism, the real work of imagination is to make contact with the strange world in which we live and to serve as both guide and inspiration for our development within it. It is the way we evolve. Imagination presents us with possible, potential realities that it is our job to actualize. It also presents us with a world that would not be complete without our help.
Let us look then for this lost knowledge of the imagination, and see how much of it we can find.
 It is a phenomenon, in Sir William Grove’s words, ‘so obvious to simple apprehension that to define it would make it more obscure’. Quoted in Samuel Butler ‘Thought and Language’ in The Importance of Language ed. Max Black (Ithaca, NY: Cornell University Press, 1969) p. 13.