It's true what they say, by the way -- everything you need to know is in those books. All of your cutting edge buzz-concepts existed from the very beginning. But, I understand: you need to get tenure, etc.
Anyway, I just wanted to drop a plug for Plotinus' (204-270 AD) Enneads. This won't be for everybody, but if you're interested in a synthesis of all of the great theology and philosophy of the ancient world, if you're interested in the fountainhead of the mystic traditions of Paganism, Judaism, Christianity, Islam, and Gnosticism, this is it. It's very ethereal, profoundly metaphysical in flavor, but the Penguin edition is "an interpretive translation" by Stephen MacKenna, heralded as one of the great translations of the 20th century.
I understand why people get balky (is that a word?) around the old stuff -- it's difficult, and sometimes it seems to make persistent reference to bizarre-sounding concepts. Consider this passage from Plotinus:
Wisdom and understanding consist in the contemplation of all that exists in the Intellectual-Principle, and the Intellectual-Principle itself apprehends this all (not by contemplation but) as an immediate presence.
And each of these has two modes according as it exists in the Intellectual-Principle and in the Soul: in the Soul it is Virtue, in the Supreme not Virtue.
In the Supreme, then, what is it?
Its proper Act and Its Essence.
That Act and Essence of the Supreme, manifested in a new form, constitute the virtue of this sphere. For the Ideal-Form of Justice or of any other virtue is not itself a virtue, but, so to speak, an exemplar, the source of what in the Soul becomes virtue: for virtue is dependent, seated in something not itself; the Ideal-Form is self-standing, independent.
I have bold-faced some of the words that I think might give even the most literate people difficulty on a first read. But Plotinus is careful to define his terms as his argument develops, and all that seems required is deliberate reading and, perhaps, some occasional marginalia. Five years ago, I was unprepared to read this kind of text; I would have said, "It's mumbo-jumbo, hogwash. I don't have the patience for this."
But I did one thing right. I blamed it on me (lacking patience), and not on Plotinus. It is difficult to "shotgun" 12-ounces of wine, and very few people would want to -- and it is no different with Plotinus. If you decide to try him, take him out on your balcony during the sunset hours and be prepared to slow down.
Says wikipedia, "According to the account of Eustochius, who attended him at the end, Plotinus' final words were: 'Strive to give back the Divine in yourselves to the Divine in the All.' Eustochius records that a snake crept under the bed where Plotinus lay, and slipped away through a hole in the wall; at the same moment the philosopher died."
Hmm... hey, haven't I heard this one before?