was done solely for his friend David's sake.

He wrote a long letter to his Louise; he felt bolder, pen in hand,
than face to face. In a dozen sheets, copied out three several times,
he told her of his father's genius and blighted hopes and of his
grinding poverty. He described his beloved sister as an angel, and
David as another Cuvier, a great man of the future, and a father,
friend, and brother to him in the present. He should feel himself
unworthy of his Louise's love (his proudest distinction) if he did not
ask her to do for David all that she had done for him. He would give
up everything rather than desert David Sechard; David must witness his
success. It was one of those wild letters in which a young man points
a pistol at a refusal, letters full of boyish casuistry and the
incoherent reasoning of an idealist; a delicious tissue of words
embroidered here and there by the naive utterances that women love so
well--unconscious revelations of the writer's heart.

Lucien left the letter with the housemaid, went to the office, and
spent the day in reading proofs, superintending the execution of
orders, and looking after the affairs of the printing-house. He said
not a word to David. While youth bears a child's heart, it is capable
of sublime reticence. Perhaps, too, Lucien began to dread the
Phocion's axe which David could wield when he chose, perhaps he was
afraid to meet those clear-sighted eyes that read the depths of his
soul. But when he read Chenier's poems with David, his secret rose
from his heart to his lips at the sting of a reproach that he felt as
the patient feels the probing of a wound.