Marsilio Ficino’s Platonic Theology, Volume II

3But this will be explained more clearly as follows. If the mind’s operation properly terminates in the mind itself, then the mind is in a certain manner the end of its own operation. The end and principle of each thing are the same, since all things desire their origin and set it before themselves as the end of their motion. The substance of the mind is therefore the principle of its own operation. It consequently operates through itself, which our Plato calls self-motion. As the mind operates, so it lives; for life is inward operation. It therefore lives through itself. As it lives, so it also exists, for life is the first act of existence. It likewise exists, then, through itself. What prevents it from existing always, since it is its own cause? I mean not an efficient cause, but a formal cause, by whose power being is bestowed and preserved. A quality and a life whose every operation flows into other things necessarily fail in four respects according to their own nature. First, because in flowing out they waver and need support from another. Second, in streaming away they are weakened. Third, while flowing into other things they are sullied by what is foreign. Fourth, because of need, weakness, and defilement they are at times compelled to ebb away from their own nature. If this is so, it follows that rational life, which flows back into itself, sustains itself, is not weakened or defiled, and does not ebb away. Accordingly, just as a life compelled to flow wholly outside itself departs from life and tends toward and is consumed in death, so a life that overflows back into itself grows and is consummated in life. Finally, if fuller motion is a sign of fuller life, then rational life, which exercises, brings to fullness, and terminates the whole range of motion, likewise brings the whole range of living to fullness. Therefore neither any privation of life nor any condition subject to death is mingled with it. We have shown elsewhere that rational life exercises every species of motion in the body, brings the exemplars of all motions to fullness within itself, and through the mind’s own reflections brings every motion to its end in itself and in its own principle.