Shadow is the diminution alike of light and of darkness, and stands between darkness and light. - Leonardo da Vinci

Darkness is absence of light. Shadow is diminution of light.

Since the wings are swifter to press the air than the air is to escape from beneath the wings the air becomes condensed and resists the movement of the wings; and the motive power of these wings by subduing the resistance of the air raises itself in a contrary movement to the movement of the wings.

Verrà il tempo in cui l’uomo non dovrà più uccidere per mangiare, ed anche l’uccisione di un solo animale sarà considerato un grave delitto

as a well-spent day gives, joy in sleep
so a well-spent life brings, joy in dying