Teaching an ass to obey the rein, which the ancients thought to be nearly as difficult as to wash a blackamoor white, or to do any other impossible thing, «Labour in vain». Though I think it is not now found to be so difficult, and those animals are made to serve for many useful purposes. The adage is used by Horace, and with much elegance, in his first Satire.
«At si cognatos nullo natura labore
Quos tibi dat, retinere velis, servareque amicos;
Infelix operam perdas; ut si quis asellum
In campo doceat parentem currere frœnis».
But if you expect to obtain the affection of your relations, or to preserve the esteem of your friends, without making any return for their kindness, you will find yourself, wretch that you are, miserably deceived, as he would be, who should attempt to reach an ass to be obedient to the rein.

More crafty than the cuckoo. The cuckoo is never at the pains of building a nest, but having found one belonging to some other bird, fit for her purpose, she throws out the eggs she finds in it, and deposits her own in their place. The owner of the nest, not perceiving the fraud, hatches the cuckoo's egg, and nurtures the young one, thus freeing its mother from all care for her offspring. The cuckoo is a bird of passage; it appears in this country in the month of April, and leaves it in June. The female lays only a single egg, usually in the nest of the hedge-sparrow, as we learn from the following distich.

«The hedge-sparrow fed the cuckoo so long,
That she had her head bit off by her young».
(Shakespeare, King Lear, Act 1, Scene 4)