Unless It Is First Known

The acquisition of any knowledge is always of use to the intellect, because it may thus drive out useless things and retain the good.  For nothing can be loved or hated unless it is first known.

-- Leonardo da Vinci (1452 - 1519), Italian Renaissance painter, architect, inventor, scientist, and sculptor, The Notebooks of Leonardo da Vinci (1883) XIX Philosophical Maxims.  Morals.  Polemics and Speculations