Thomas Hardy, Tess of the d'Urbervilles

"She philosophically noted dates as they came past in the revolution of the year… her own birthday; and every other day individualized by incidents in which she had taken some share. She suddenly thought one afternoon, when looking in the glass at her fairness, that there was yet another date, of greater importance to her than those; that of her own death, when all these charms would have disappeared; a day which lay sly and unseen among all the other days of the year, giving no sign or sound when she annually passed over it; but not the less surely there. When was it?"