For it is not possible to join serpentine wisdom with columbine innocence, except men know exactly all the conditions of the serpent: his baseness and going upon his belly, his volubility and lubricity, his envy and sting, and the rest; that is, all forms and natures of evil: for without this, virtue lieth open and unfenced.

The Works of Francis Bacon, Baron of Verulam, Viscount St. Alban, and Lord High Chancellor of England (ed. 1778)