Quae uncis sunt unguibus ne nutrias

Do not feed, or take under your roof animals of ferocious and savage dispositions, that have sharp and crooked claws. Do not cherish a snake in your bosom, or enter into friendship with crafty and deceitful persons. Otez un vilain du gibet, il vous y mettra, save a thief from the gallows, and he will cut your throat. Cría el cuervo, y sacarte ha los ojos, breed up a crow and he will tear out your eyes. Ingratitude and the unyielding bent of nature were typified by the Greeks under the elegant representation of a goat giving suck to the whelp of a wolf, with a subscription, which has been thus rendered.
«A wolf reluctant with my milk I feed,
Obedient to a cruel master's will;
By him I nourish'd, soon condemned to bleed,
For stubborn nature will be nature still».
We may add two familiar lines to these,
«The hedge-sparrow fed the cuckoo so long,
That she had her head bit off by her young».