Lincoln Paine, The Sea and Civilization (p. 130):
Octavian’s victory in Egypt brought the entire Mediterranean basin under the command of a single imperial rule. To guarantee the safety of the empire and its sea trade, Augustus (as Octavian styled himself) established Rome’s first standing navy, with bases at Misenum just south of Portus ]ulius, and at Ravenna in the northern Adriatic. These fleets comprised a variety of ships from liburnians to triremes, “fours,” and “fives.” As the empire expanded, provincial fleets were established in Egypt, Syria, and North Africa; on the Black Sea; on the Danube and Rhine Rivers, which more or less defined the northern border of the empire; and on the English Channel. Over the next two centuries there was nearly constant fighting on the empire’s northern and eastern borders, but the Mediterranean experienced a period of unprecedented peace and prosperity during which Greco-Roman culture circulated easily around what everyone was entitled to call Mare Nostrum – Our Sea. It was the only time that the Mediterranean has ever been under the aegis of a single power, with profound results for all the cultures that subsequently emerged on its shores.
There follows (p. 132) a description of the sort of commercial culture that resulted. Here is some of what Paine says about Ostia:
The remains of the city, which rival those of Pompeii, reveal a town of ordinary citizens rather than wealthy estate owners and their retinues. The essentially rectilinear streets were lined with three- and four-story apartment houses, many with street-level stores and offices. …
But then, concerning religion in Ostia, Paine addes this:
… In addition to houses, offices, workshops, and laundries, the city boasted an astonishing array of religious buildings that reflect the inhabitants’ strong ties to the Roman east. Side-by-side with temples to the gods of the Greco-Roman pantheon and the imperial cults stand Christian baptisteries, a Jewish synagogue, and a host of temples to Near Eastern deities, including a dozen dedicated to the Zoroastrian divinity Mithras, the god of contracts and thus revered by merchants. …
Mithras was the god of contracts? Revered by merchants? I knew about how the Roman Empire took off economically (and degenerated politically) by surrounding the Mediterranean, but I did not know that Mithras was the god of contracts and was revered by merchants. So, it would appear that proto-libertarianism in the ancient world missed a big chance when Christianity conquered the Roman Empire and prevailed over Zoroastrianism. Although, a little preliminary googling tells me that some reckon Christianity to have been “borrowed” from Zoroastrianism. Whatever. I like the sound of it, and will investigate it more. By which I mean I will do some investigating of it, instead of the zero investigating of it that I have done so far in my life.