Cosimo de' Medici had commissioned Ficino to translate the complete works of Plato into Latin, the first time that had been done, and in 1462, with the work underway, a manuscript of the Corpus Hermeticum arrived from Macedonia and Cosimo told him to stop and translate that first.
The instruction is the single most revealing fact about Renaissance Hermeticism. The Hermetic texts were believed to be Egyptian and older than Moses, and therefore closer to the source of a prisca theologia, an original revelation given to the gentiles and transmitted through Hermes, Orpheus, Pythagoras and Plato to the Christian present. Plato could wait, because Plato was downstream. That chronology was wrong by well over a millennium, as Casaubon showed in 1614, and the entire structure of the Florentine revival was built on it.
Ficino's own contribution is De vita libri tres (1489), and the third book, On Obtaining Life from the Heavens, is the founding text of Renaissance natural magic. It is a physician's book, written for scholars whose melancholy he took to be an occupational disease of Saturn, and its prescriptions are correspondences put to therapeutic use: eat, wear, look at, smell and above all sing things that belong to the beneficent planets, and the celestial influence they carry will reach the spiritus, the subtle vehicle between body and soul. The Orphic hymns he sang to his own lyre were the operative part.
He was careful about what he was claiming, and D. P. Walker's study is the standard account of just how careful he had to be. His magic is presented as natural, the manipulation of a real physical sympathy running through creation, involving no spirits and therefore no demons and no idolatry. Whether the line holds is doubtful, and Ficino knew it was doubtful: a priest drawing down planetary influence by hymn and talisman is doing something the church had condemned. He was investigated for magic around 1489-90 and survived it through powerful friends and a prompt apologia.