Ante-Nicene Fathers, Vol III:
Tertullian: Part I: Whither Does the Soul Retire When It Quits the Body? Opinions of Philosophers All More or Less Absurd. The Hades of Plato.

Chapter LIV.—Whither Does the Soul Retire When It Quits the Body?  Opinions of Philosophers All More or Less Absurd. The Hades of Plato.

To the question, therefore, whither the soul is withdrawn, we now give an answer. Almost all the philosophers, who hold the soul’s immortality, notwithstanding their special views on the subject, still claim for it this (eternal condition), as Pythagoras, and Empedocles, and Plato, and as they who indulge it with some delay from the time of its quitting the flesh to the conflagration of all things, and as the Stoics, who place only their own souls, that is, the souls of the wise, in the mansions above. Plato, it is true, does not allow this destination to all the souls, indiscriminately, of even all the philosophers, but only of those who have cultivated their philosophy out of love to boys. So great is the privilege which impurity obtains at the hands of philosophers!  In his system, then, the souls of the wise are carried up on high into the ether: according to Arius, 1797 into the air; according to the Stoics, into the moon. I wonder, indeed, that they abandon to the earth the souls of the unwise, when they affirm that even these are instructed by the wise, so much their superiors.  For where is the school where they can have been instructed in the vast space which divides them? By what means can the pupil-souls have resorted to their teachers, when they are parted from each other by so distant an interval?  What p. 231 profit, too, can any instruction afford them at all in their posthumous state, when they are on the brink of perdition by the universal fire? All other souls they thrust down to Hades, which Plato, in his Phædo, 1798 describes as the bosom of the earth, where all the filth of the world accumulates, settles, and exhales, and where every separate draught of air only renders denser still the impurities of the seething mass.

Footnotes

An Alexandrian philosopher in great repute with the Emperor Augustus.

Phædo, pp. 112–114.