From LOST IN THE COSMOS by Walker Percy
Why Writers Drink
He is marooned in his cortex. Therefore it is his cortex he must assault. Worse, actually. He, his self, is marooned in his left cortex, locus of consciousness according to Eccles. Yet his work, if he is any good, comes from listening to his right brain, locus of the unconscious knowledge of the fit and form of things. So, unlike the artist who can fool and cajole his right brain and get it going by messing in paints and clay and stone, the natural playground of the dreaming child self, there sits the poor writer, rigid as a stick, pencil poised, with no choice but to wait in fear and trembling until the spark jumps the commissure. Hence, his notorious penchant for superstition* and small obsessive and compulsive acts such as lining up paper exactly foursquare with desk. Then, failing in these frantic invocations and after the right brain falls as silent as the sphinx--what else can it do?--nothing remains, if the right won't talk, but to assault the left with alcohol, which of course is a depressant and which does of course knock out that grim angel guarding the gate of Paradise and let the poor half-brained writer in and a good deal else besides. But by now the writer is drunk, his presiding left-brained craftsman-consciousness laid out flat, trampled by the rampant imagery from the right and a horde of reptilian demons from below.
*Graham Greene, albeit a Christian, was observed by Evelyn Waugh to perform a curious rite before he could get to work. He went out to the street and watched the stream of traffic. When asked what he was doing, he replied that he was waiting for a particular combination of numbers to turn up on a license plate--777. When it did, he went cheerfully to his writing desk.