O, mickle is the powerful grace that lies
In herbs, plants, stones, and their true qualities:
For nought so vile that on the earth doth live
But to the earth some special good doth give,
Nor aught so good but strain’d from that fair use
Revolts from true birth, stumbling on abuse:
Virtue itself turns vice, being misapplied;
And vice sometimes by action dignified.
Within the infant rind of this small flower
Poison hath residence and medicine power:
For this, being smelt, with that part cheers each part;
Being tasted, slays all senses with the heart.
Two such opposed kings encamp them still
In man as well as herbs, grace and rude will;
And where the worser is predominant,
Full soon the canker death eats up that plant.

Autore: William Shakespeare