As a result of his academic excellence - especially in Literature and Latin - he was accepted among the Jesuits at the age of fifteen. He made an intense novitiate in the dependencies of the Order, in Talca, Concepción and Santiago. He lived on the estate of Bucalemu, a former Jesuit convict, in the area known today as El Convento in the El Yali wetland.In that silent and pacific solitudes, he revived his intellectual work that would later make him known, Molina delved into the study of the classics and the natural sciences. His progress was very fast and within five years (Molina was 20 years old to date) he already had a solid knowledge of Latin, Greek, French and Italian. That merit led him to be transferred in 1760 to the Jesuit residence in Santiago, where he worked as a librarian. In 1761, in a room at the Universidad Pontificia Colegio Máximo de San Miguel, Molina renounced the will of his assets. He only set aside 100 pesos from his dispossession, that were reserved for the purchase of books.