Because you will see the letter, not the first one he ever wrote to her but at least the first, the only one she ever showed, as your grandmother knew then: and, so we believe now that she is dead, the only one which she kept unless of course Miss Rosa or Clytie destroyed the others after she herself died: and this one here preserved not because Judith put it away to keep but because she brought it herself and gave it to your grandmother after Bon's death, possibly on the same day when she destroyed the others which he had written her (provided of course it was she herself who destroyed them) which would have been when she found in Bon's coat the picture of the octoroon mistress and the little boy. Because he was her first and last sweetheart. She must have seen him in fact with exactly the same eyes that Henry saw him with. And it would be hard to say to which of them he appeared the more splendid — to the one with hope, even though unconscious, of making the image hers through possession; to the other with the knowledge of the insurmountable barrier which the similarity of gender hopelessly intervened — this man whom Henry first saw riding perhaps through the grove at the University on one of the two horses which he kept there or perhaps crossing the campus on foot in the slightly Frenchified cloak and hat which he wore, or perhaps (I like to think this) presented formally to the man reclining in a flowered, almost feminized gown, in a sunny window in his chambers — this handsome elegant and even catlike and too old to be where he was, too old not in years but in experience, with some tangible effluvium of knowledge, surfeit: of actions done and satiations plumbed and pleasures exhausted and even forgotten. So that he must have appeared, not only to Henry but to the entire undergraduate body of that small new provincial college, as a source not of envy, because you only envy whom you believe to be, but for accident, in no way superior to yourself: and what you believe, granted a little better luck than you have had heretofore, you will someday possess not of envy but of despair: that sharp shocking terrible hopeless despair of the young which sometimes takes the form of insult toward and even physical assault upon the human subject of it or, in extreme cases like Henry's, insult toward and assault upon any and all detractors of the subject, as witness Henry's violent repudiation of his father and his birthright when Sutpen forbade the marriage. Yes, he loved Bon, who seduced him as surely as he seduced Judith the country boy born and bred who, with the five or six others of that small undergraduate body composed of other planters' sons whom Bon permitted to become intimate with him, who aped his clothing and manner and (to the extent which they were able) his very manner of living, looked upon Bon as though he were a hero out of some adolescent Arabian Nights who had stumbled upon a talisman or touchstone not to invest him with wisdom or power or wealth, but with the ability and opportunity to pass from the scene of one scarce imaginable delight to the next one without interval or pause or satiety. And the very fact that, lounging before them in the outlandish and almost feminine garments of his sybaritic privacy, the professed satiety only increased the amazement and the bitter and hopeless outrage. Henry was the provincial, the clown almost, given to instinctive and violent action rather than to thinking who may have been conscious that his fierce provincial's pride in his sister's virginity was a false quantity which must incorporate in itself an inability to endure in order to be precious, to exist, and so must depend upon its loss, absence, to have existed at all. In fact, perhaps this is the pure and perfect incest: the brother realizing that the sister's virginity must be destroyed in order to have existed at all, taking that virginity in the person of the brother-in-law, the man whom he would be if he could become, metamorphose into, the lover, the husband; by whom he would be despoiled, choose for despoiler, if he could become, metamorphose into the sister, the mistress, the bride.
Perhaps that is what Went on, not in Henry's mind but in his soul. Because he never thought. He felt, and acted immediately.
He knew loyalty and acted it, he knew pride and jealousy; he loved grieved and killed, still grieving and, I believe, still loving Bon, the man to whom he gave four years of probation, four years in which to renounce and dissolve the other marriage, knowing that the four years of hoping and waiting would be in vain.