While she was still sick she begged her parents to intercede with the Sisters of Penance and learn if they would not admit her to their order as a novice. Giacomo and Lapa, now realizing that their extraordinary daughter would be happy in no other kind of life, went to the Sisters with this request. They were told that it was contrary to all the customs of the Sisters to admit young girls. The parents pleaded, and finally some of the Sisters agreed to go to Benincasa's house to see his daughter. They found Catherine very thin and pale, and listened to her story of how she had long before renounced all the pleasures and vanities of this world. She talked so earnestly that the Sisters were convinced, and as a result agreed a little later that she should be admitted to their number. At this news Catherine wept for joy, and gave fervent thanks to St. Dominic, praying that she might soon be well enough to receive the holy mantle of the Sisterhood. Her joy soon brought back her health, and shortly she was able to be out again, and to take the vows required of one who entered the Order, or the Mantellate, as the Sisters were called from the black mantle which they habitually wore. This was in 1364, when she was about seventeen years old. After that Catherine spent several years largely in solitude, although her passion for flowers led her to cultivate a little garden, and her desire to read the writings of the Church caused her to study reading. She had never learned this at home, but now she asked one of the Sisters to teach her the alphabet, and when she had learned that, she set to work to learn to read. After many weeks of hard study she was finally able to say that she could read the various Offices of the Church. If Catherine Benincasa had continued her life as a Sister of Penance she would have been simply one of many women who have dedicated their lives to withdrawing from the world and following the course of their own thoughts. She would have left no record of her works behind her nor would she have had much influence on her time. But as it happened she became a great influence, one of the most remarkable women of her century in Europe, and the person of whom the old city of Siena was most proud. She was continually seeing visions of what she was to do, and she followed their commands without hesitation. As a result she accomplished many remarkable things, most of which would have seemed impossible to even the strongest woman.