Indeed the romance of Malory makes Arthur deserve "the pretty popular
name such manhood earns" by his conduct as regards Guinevere when she
is accused by her enemies in the later chapters. Yet Malory does not
finally condone the sin which baffles Lancelot's quest of the Holy
Grail.

Tennyson at first was in doubt as to writing on the Grail, for
certain respects of reverence. When he did approach the theme it was
in a method of extreme condensation. The romances on the Grail
outrun the length even of mediaeval poetry and prose. They are
exceedingly confused, as was natural, if that hypothesis which
regards the story as a Christianised form of obscure Celtic myth be
correct. Sir Percivale's sister, in the Idyll, has the first vision
of the Grail:-


"Sweet brother, I have seen the Holy Grail:
For, waked at dead of night, I heard a sound
As of a silver horn from o'er the hills
Blown, and I thought, 'It is not Arthur's use
To hunt by moonlight'; and the slender sound
As from a distance beyond distance grew
Coming upon me--O never harp nor horn,
Nor aught we blow with breath, or touch with hand,
Was like that music as it came; and then
Stream'd thro' my cell a cold and silver beam,
And down the long beam stole the Holy Grail,
Rose-red with beatings in it, as if alive,
Till all the white walls of my cell were dyed