The General Preface.

Marcus Cicero once said, "I will follow Reason, wherever it leads me" original Latin: "Marcus Cicero, Rationem, quò ea me cunque ducet, fequar"; I consider that I began then to honor my office original: "Function", and among other priestly garments original: "Habiliments", in particular to put on the Logion original Greek: Λόγιον, meaning the "Oracle" or "Word" or Rationale The "Rationale" refers to the Breastplate of Judgment worn by the High Priest of Israel, symbolizing wisdom and divine light., the priestly breastplate, which most justly claims its place in that region which is the seat of the heart; the simplicity and sincerity of that part being the root or well-spring of the soundest and purest reason. And truly I cannot well imagine what the moral reason might be why Aaron's robes should be such an express representation of the universe ("a reflection and a kind of imitation of the universe," original Greek: ἀπηύγασμα καὶ μίμημά τι τοῦ κόσμου as Philo Philo of Alexandria (c. 20 BCE – 50 CE) was a Jewish philosopher who blended Greek philosophy with biblical tradition.
Philo, On Monarchy*.

calls it) unless every priest should endeavor, according to his opportunity and capacity, to be also as much as he can a rational man or philosopher. (For which reason certainly universities were first established, and are still continued to this very day.) And Philo himself hints at something to this purpose: "For it is intended that the High Priest should have an image of the universe about him, so that from the constant sight of it he may make his own life worthy of the nature of the whole" original Greek: Βούλεται γὰρ τὸν ἀρχιερέα εἰκόνα τοῦ παντὸς ἔχειν ἐμφερῆ, ἵνα ἐκ τῆς συνεχοῦς θέας ἄξιον παρέχῃ τὸν ἴδιον βίον τῆς τῶν ὅλων φύσεως. That the High Priest, continually reflecting upon his attire which represented the universe, might be reminded not to do or speak anything contrary to its laws, or contrary to the rules of eternal Reason,
In his On Dreams*.

which is that everlasting High Priest, as Philo elsewhere indicates: "For there are, as it seems, two temples of God: one is this world, in which the High Priest is His first-born, the Divine Word (Logos), or eternal wisdom; the other is the rational soul, whose priest is the true man" original Greek: Δύο γάρ, ὡς ἔοικεν, ἱερὰ Θεοῦ· ἓν μὲν ὅδε ὁ κόσμος, ἐν ᾧ καὶ ἀρχιερεὺς ὁ πρωτόγονος αὐτοῦ, ὁ θεῖος λόγος· ἕτερον δὲ ἡ λογικὴ ψυχή, ἧς ἱερεὺς ὁ πρὸς ἀλήθειαν ἄνθρωπος—that is to say, the intellect, (as Plotinus Plotinus (c. 204–270 CE) was the primary philosopher of Neoplatonism. says somewhere) and which is the image of the Divine Word (Logos), as Clement Clement of Alexandria (c. 150–215 CE) was a Christian theologian who integrated Greek philosophy into the faith. has expressed it.
Stromata, book 5.

"For the image of God is the royal and divine Word (Logos), the man free from passion original: "impassible Man"; but the image of this image is the human intellect" original Greek: Εἰκὼν μὲν γὰρ Θεοῦ λόγος θεῖος καὶ βασιλικός, ἄνθρωπος ἀπαθής, εἰκὼν δ' εἰκόνος ἀνθρώπινος νοῦς.

So that though the Divine Reason or Word (Logos) be that eternal High Priest which in time was to be incarnate Take on human form, referring to Jesus Christ., and of which Aaron in his priestly robes was but a type A symbolic foreshadowing. and figure; yet man being an image of Him, and every priest in a more special manner, he is to endeavor to adorn himself with such accomplishments as are set out by these rich and precious garments of Aaron; among which the Rationale had a chief place. For though it belongs to that everlasting Word (Logos) alone to be the maker of the world, and to fill out all parts of it by His presence, and to be in a manner vitally clothed with it; yet through the goodness of God it may fall to the share of every Christian priest to be invested, as it were, and adorned with the knowledge of the laws and measures of the creation, and to take notice of the reasons of nature of which the eternal Word is the maker and governor. This is very consistent with what Philo writes of the shape of the Rationale or priestly breastplate, which he says was square, "because the reason of universal nature and of man must be established firmly on all sides, and not waver in any respect" original Greek: ὅτι χρὴ καὶ τὸν φύσεως λόγον καὶ τὸν τοῦ ἀνθρώπου βεβηκέναι πάντῃ, καὶ κατὰ μηδ' ὁτιοῦν κραδαίνεσθαι. As these things were symbolized original: "figured" in Aaron, and are fulfilled immensely in Christ, so they are also in their measure to be fulfilled in the Christian priesthood. For if it were not lawful to offer up the blind or lame under the Law, surely the priest ought