temporal, for that which is properly eternal, and such is intellect, is
perfectly stable, and has no transitive energies, hence it is necessary
that its motions should be periodic. For motion is a certain mutation
from some things into others. And beings are terminated by multitudes and
magnitudes. These therefore being terminated, there can neither be an
infinite mutation, according to a right line, nor can that which is
always moved proceed according to a finished progression. Hence that
which is always moved will proceed from the same to the same; and will
thus form a periodic motion. Hence, too, the human, and this also is true
of every mundane soul, uses periods and restitutions of its proper life.
For, in consequence of being measured by time, it energizes transitively,
and possesses a proper motion. But every thing which is moved perpetually
and participates of time, revolves periodically and proceeds from the
same to the same. And hence the soul, from possessing motion, and
energizing according to time, will both possess periods of motion and
restitutions to its pristine state.

Again, as the human soul, according to Plato, ranks among the number of
those souls that sometimes follow the mundane divinities, in consequence
of subsisting immediately after daemons and heroes, the perpetual
attendants of the gods, hence it possesses a power of descending
infinitely into generation, or the sublunary region, and of ascending
from generation to real being. For since it does not reside with divinity
through an infinite time, neither will it be conversant with bodies
through the whole succeeding time. For that which has no temporal
beginning, both according to Plato and Aristotle, cannot have an end; and
that which has no end, is necessarily without a beginning. It remains,
therefore, that every soul must perform periods, both of ascensions from
generation, and of descensions into generation; and that this will never
fail, through an infinite time.