Sallustius or Sallust was a 4th-century writer, a friend of the Roman Emperor Julian. He wrote the treatise On the Gods and the Cosmos, a kind of catechism of 4th-century Hellenic paganism. Sallustius' work owes much to that of Iamblichus of Chalcis, who synthesized Platonism with Pythagoreanism and theurgy, and also to Julian's own philosophical writings. The treatise is quite concise, and generally free of the lengthy metaphysical theorizing of the more detailed Neoplatonic texts. Its aim is in part "to parry the usual onslaughts of Christian polemic" in the face of Christianity's growing preeminence, and "me[e]t theology with theology"
The first of these is the production of Sallust, a Neo Platonic philosopher, who is considered by Gale as the same Sallust that, according to Suidas, was cotemporary with Proclus, and who appears to have been alive when Simplicius wrote his Commentaries on Epictetus: but though the testimony of Suidas, or rather Damascius, from whose History of Philosophers Suidas derived his account of Sallust, is very decisive as to the existence of a philosopher of this name, yet there are two particulars which, in my opinion, render it very doubtful whether the author of the present treatise is the Sallust mentioned by Suidas. The first is, that the Sallust of Suidas is said to have asserted, “that it was not easy, but rather impossible, for men to philosophize;” an assertion, as Damascius well observes, which is neither true, nor worthy to be uttered, and which is certainly very inconsistent with what the author of the present treatise asserts: for (in Chap. XIII.) he informs us, that his book was composed for that class of mankind whose souls may be considered as neither incurable, nor yet capable of being elevated by philosophy; plainly acknowledging by this, that some men are capable of philosophizing in a proper manner, and thus evidently contradicting the dogma of the Sallust mentioned by Damascius and Suidas. But there is another particular which militates against this opinion, and which is of no less weight than that we have just now mentioned; and this is, the disagreement which is related by Suidas to have taken place between Sallust and Proclus; for the author of the following book, as was obvious to the learned philologist Gale, treads every where in the footsteps of Proclus: not to mention that the Sallust of Suidas, by composing Orations after the manner of the antients, and philosophizing like the Cynics, can hardly be supposed to be that profound philosopher who wrote the ensuing treatise On the Gods and the World.
It is, however, sufficient for our purpose, that the work itself is fortunately preserved entire, whatever uncertainty we may labour under concerning its real author; I say fortunately preserved, for it may be considered as a beautiful epitome of the Platonic philosophy, in which the most important dogmas are delivered with such elegant conciseness, perfect accuracy, and strength of argument, that it is difficult to say to which the treatise is most intituled—our admiration or our praise. I have before observed, that this little work was composed by its author with a view of benefiting a middle class of mankind, whose souls are neither incurable, nor yet capable of ascending through philosophy to the summit of human attainments: but in order to understand this distinction properly, it is necessary to inform the reader, that human souls may be distributed into three ranks; into such as live a life pure and impassive when compared with the multitude; into such as are neither wholly pure nor yet perfectly impure; and into such as are profoundly impure. Souls of the first class, which are consequently the fewest in number, may be called divine souls, heroes and demigods, and when invested with a terrene body, form such men as Pythagoras, Plato, Plotinus, Jamblichus, Proclus, &c., were of old: souls of this kind, not only descend into mortality in consequence of that necessity by which all human souls are at times drawn down to the earth, but for the benevolent purpose of benefiting such as are of an inferior class; they likewise easily recover a remembrance of their pristine state, and, in consequence of this, descend no farther than to the earth. But souls of the middle class, for whom the book of Sallust is designed, in consequence of becoming vitiated and defiled, though not in an incurable degree, are incapable of acquiring in the present life philosophic perfection and purity, and are with great difficulty, and even scarcely able to ascend, after long periods, to the beatific vision of the intelligible world. But souls of the third class, are such as, from their profound impurity, and from having drank immoderately deep of oblivion, may be considered as abiding perpetually in life, as in the dark regions of Tartarus, from which, through having lost all freedom of the will, they can never emerge.
But we may easily collect the propriety of this distribution, by considering, that there must necessarily be two mediums between souls that abide on high with purity, such as the souls of essential heroes, who are perpetual attendants on the gods, and souls that descend with the greatest impurity; and these mediums can be no other than souls that descend indeed, but with purity, and souls that descend, and are partly pure and partly impure.