When at last he became a great preacher, able to sway heart and conscience, it should not be forgotten that he was mediæval to the core. His doctrinal teaching was based firmly on the theology of Thomas Aquinas. His intellectual conception of faith, his strong belief in the divine predestination and his way of expressing it, his view of Scripture as possessing manifold meanings, were all defined for him by the great Dominican Schoolman. He held strongly the mediæval idea that the Church was an external political unity, ruled by the Bishop of Rome, to whom every human soul must be subject, and whom everyone must obey save only when commands were issued contrary to a plain statement of the evangelical law. He expounded the fulness of and the slight limitations to the authority of the Pope exactly as Thomas and the great Schoolmen of the thirteenth century had done, though in terms very different from the canonists of the Roman Curia at the close of the Middle Ages. Even his appreciation of the Neo-Platonist side of Humanism could be traced back to mediæval authorities; for at all times the writings of the pseudo-Dionysius had been a source of inspiration to the greater Schoolmen. His scholarship brought him into relation with the Humanist leaders in Florence, the earnest tone of his teaching and the saintliness of his character attracted them, his deep personal piety made them feel that he possessed something which they lacked; while no Neo-Platonist could be repelled by his claim to be the recipient of visions from on high. The celebrated Humanists of Florence became the disciples of the great preacher. Marsiglio Ficino himself, the head of the Florentine Academy, who kept one lamp burning before the bust of Plato and another before an image of the Virgin, was for a time completely under his spell. Young Giovanni Pico della Mirandola’s whole inner life was changed through his conversations with the Prior of San Marco. He reformed his earlier careless habits. He burnt five books of wanton love-songs which he had composed before his conversion.(106) He prayed daily at fixed hours, and he wrote earnestly to his nephew on the importance of prayer for a godly life: