Martin R.P. McGuire, S. Ambrosii De Nabuthae: A Commentary, with an Introduction and Translation
(Washington: The Catholic University of America, 1927), pp. 82-85 (13.54):
Why do you boast of your noble lineage? You are even wont to go over the pedigrees of your dogs as you do those of wealthy men, you are even wont to praise the nobility of your horses as you do that of the consuls. That horse was sired by that father and born of that mother; this one rejoices in that grandsire, that one boasts of even more remote ancestry. But this is of no aid to him in the race; the palm is not given for noble lineage, but for running.
quid te iactas de nobilitatis prosapia? soletis et canum uestrorum origines sicut diuitum recensere, soletis et equorum uestrorum nobilitatem sicut consulum praedicare. ille ex illo patre generatus est et ex illa matre editus, ille auo gaudet, ille se proauis adtollit. sed nihil istud currentem iuuat; non datur nobilitati palma, sed cursui.
In his commentary (p. 184), McGuire compares Juvenal 8.56-61, here in G.G. Ramsay's translation:
Tell me, thou scion of the Trojans, who deems a
dumb animal well-born unless it be strong?
It is for
this that we commend the swift horse whose speed sets
every hand aglow, and
fills the Circus with the hoarse
shout of victory; that horse
is noblest, on whatever
is foremost upon the plain.
dic mihi, Teucrorum proles, animalia muta
quis generosa putet nisi fortia. nempe volucrem
sic laudamus equum, facili cui plurima palma
fervet et exultat rauco victoria circo;
nobilis hic, quocumque venit de gramine, cuius 60
clara fuga ante alios et primus in aequore pulvis.