Since therefore the knowledge and survey of vice is in this world so necessary to the constituting of human virtue, and the scanning of error to the confirmation of truth, how can we more safely, and with less danger, scout intotheregions of sinand falsity thanby reading all manner of tractates and hearing all manner of reason? And this is the benefit which may be had of books promiscuously read.

-Milton,John
  Areopagitica: a speech for the liberty of unlicensed printing.