By her resolute severity, she incurred the danger of ceasing to be the object of his attachment, and of losing the gift of an immortal name, which he has conferred upon her. But Petrarch's constancy was proof against hopelessness and time. He had too fervent an admiration of her qualities, ever to change: he controlled the vivacity of his feelings, and they became deeper rooted. The struggle cost him his peace of mind. From the moment that love had seized upon his heart, the tenor of his life was changed. He fed upon tears, and took a fatal pleasure in complaints and sighs; his nights became sleepless, and the beloved name dwelt upon his lips during the hours of darkness. He desired death, and sought solitude, devouring there his own heart. He grew pale and thin, and the flower of youth faded before its time. The day began and closed in sorrow; the varieties of her behaviour towards him alone imparted joy or grief, he strove to flee and to forget; but her memory became, and for ever remained, the ruling law of his existence.[34] From this time his poetic life is dated. He probably composed verses before he saw Laura; but none have been preserved except such as celebrate his passion. How soon, after seeing her, he began thus to pour forth his full heart, cannot be told; probably love, which turns the man of the most prosaic temperament into a versifier, impelled him, at its birth, to give harmonious expression to the rush of thought and feeling that it created. Latin was in use among the learned; but ladies, unskilled in a dead language, were accustomed to be sung by the Troubadours in their native Provençal dialect. Petrarch loved Italy, and all things Italian--he perceived the melody, the grace, the earnestness, which it could embody. The residence of the popes at Avignon caused it to be generally understood; and in the language of his native Florence, the poet addressed his lady, though she was born under a less favoured sky. His sonnets and canzoni obtained the applause they deserved: they became popular: and he, no doubt, hoped that the description of his misery, his admiration, his almost idolatry, would gain him favour in Laura's heart.