Thomas De Quincey ("The Opium Eater") once said...
There is first the literature of knowledge, and secondly, the
literature of power. The function of the first is--to teach; the
function of the second is--to move, the first is a rudder, the
second an oar or a sail. The first speaks to the mere discursive
understanding; the second speaks ultimately, it may happen, to
the higher understanding or reason, but always through affections
of pleasure and sympathy.
- Thomas De Quincey ("The Opium Eater"),