“ Each man’s mind is an unknown land to himself, so that we need not be at such pains to frame a mechanism of adventure for getting to undiscovered countries. ”
 Samuel Butler, The Note-Books of Samuel Butler (1912). copy citation

add

“Only do that which insists upon being done and runs right up against you, hitting you in the eye until you do it. This calls you and you had better attend to it, and do it as well as you can. But till called in this way do nothing. Imaginary Countries Each man’s mind is an unknown land to himself, so that we need not be at such pains to frame a mechanism of adventure for getting to undiscovered countries. We have not far to go before we reach them. They are, like the Kingdom of Heaven, within us. My Books I never make them: they grow; they come to me and insist on being written, and on being such and such.” source