Lord Chesterfield, Letters to His Son
, CLXXVI (London, February 7, O.S. 1749):
I dare assert too, in defiance of the favourers of the ancients, that Homer's hero, Achilles, was both a brute and a scoundrel, and consequently an improper character for the hero of an epic poem; he had so little regard for his country, that he would not act in defence of it, because he had quarrelled with Agamemnon about a we; and then afterwards, animated by private resentment only, he went about killing people basely, I will call it, because he knew himself invulnerable; and yet, invulnerable as he was, he wore the strongest armour in the world; which I humbly apprehend to be a blunder; for a horse-shoe clapped to his vulnerable heel would have been sufficient.
Cf. F.L. Lucas, The Decline and Fall of the Romantic Ideal
(Cambridge: Cambridge University Press, 1937), p. 59: "The blunder is really his lordship's, for the legend of the hero's vulnerable heel was unknown to Homer."