The task of doing what?
Only of destroying a hope; and hope is not life, nor even youth, or strength, or sense, or capacity for work, and yet when Maurice rose from his solitary breakfast-table, and carried his letters away to his own room, although he looked and moved, and even spoke to a passing servant just as usual, he felt as if he had been suddenly paralysed, and struck down from vigorous life into the shadow of death.

He sat in his room and tried to think, but no thoughts came; only a perpetual reiteration of the words, "You and Lucia must not meet again." Over and over, and over again, the same still incomprehensible sentence kept ringing in his ears.

It was much the same thing as if some power had said to him, "You must put away from you, divorce, and utterly forget, all your past life; all your nature, as it has grown up, to this present time; and take a different individuality." The two things might equally well be said, for they were equally impossible.

He laughed as this idea struck him.

His senses were beginning to come back, and they told him plainly enough that any separation from Lucia, except by her own free choice and will, was as impossible as if they were already vowed to each other "till death us do part." There was so much comfort in this conviction that at last he was able to turn to the latter part of the letter, and to occupy himself with that mysterious yet terrible sentence, which said that Lucia, his purest and loveliest of women, whom all his long intimacy had not been able to bring down from the pedestal of honour and tender reverence on which his love had placed her, would bring a blot upon her husband's name.
In the first place, he simply and entirely refused to believe in the truth of the assertion; it was a fancy, an exaggeration at the least, and in itself, not a thing to be troubled at; but allowing that the idea could not have existed in her mother's mind without some foundation, what could that foundation be?
To consider with the most anxious investigation everything he knew of the Costellos, their life, their characters, their history, brought him some comfort, but no enlightenment.