Kingdom of Sicily (in present-day Lazio, Italy), , According to some authors, he was born in the castle of his father, Landulf of Aquino. He was born to the most powerful branch of the family, and Landulf of Aquino was a man of means. As a knight in the service of Emperor Frederick II, Landulf of Aquino held the title miles. Thomas's mother, Theodora, belonged to the Rossi branch of the Neapolitan Caracciolo family. Landulf's brother Sinibald was abbot of Monte Cassino, the oldest Benedictine monastery. While the rest of the family's sons pursued military careers, the family intended for Thomas to follow his uncle into the abbacy; this would have been a normal career path for a younger son of southern Italian nobility. At the age of five Thomas began his early education at Monte Cassino, but after the military conflict between the Emperor Frederick II and Pope Gregory IX spilled into the abbey in early 1239, Landulf and Theodora had Thomas enrolled at the studium generale (university) recently established by Frederick in Naples. There his teacher in arithmetic, geometry, astronomy, and music was Petrus de Ibernia. It was here that Thomas was probably introduced to Aristotle, Averroes and Maimonides, all of whom would influence his theological philosophy. It was also during his study at Naples that Thomas came under the influence of John of St. Julian, a Dominican preacher in Naples, who was part of the active effort by the Dominican Order to recruit devout followers. At the age of nineteen Thomas resolved to join the Dominican Order, which had been founded about 30 years earlier. Thomas's change of heart did not please his family. In an attempt to prevent Theodora's interference in Thomas's choice, the Dominicans arranged to move Thomas to Rome, and from Rome, to Paris. However, while on his journey to Rome, per Theodora's instructions, his brothers seized him as he was drinking from a spring and took him back to his parents at the castle of Monte San Giovanni Campano. Thomas was held prisoner for almost one year in the family castles at Monte San Giovanni and Roccasecca in an attempt to prevent him from assuming the Dominican habit and to push him into renouncing his new aspiration. Political concerns prevented the Pope from ordering Thomas's release, which had the effect of extending Thomas's detention. Thomas passed this time of trial tutoring his sisters