'The true exercise of imagination, in my view, is (a) To help us to understand other people (b) To respond to, and some of us, to produce art. But it has also a bad use: to provide for us, in shadowy form, a substitute for the virtues, successses, distinctions etc. which ought to be sought outside in the real world - e.g. picturing all I'd if I were rich instead of working and saving. Masturbation involves this abuse of imagination in erotic matters (which I think bad in itself) and thereby encourages a similar abuse of it in all spheres. After all the main work of life is to come out of our selves, out of the little, dark prison we are all born in. Masturbation is to be avoided as all things are to be avoided which retard this process. The danger is that of coming to love the prison.'
CS Lewis in Walter Hooper (Ed.), The Collected Letters of CS Lewis Vol III, p.759.
