It's a rather well known little known fact that Jesus shares his birthday with the Roman God Mithra. (or Mithras) The later Roman emperors appropriated the celebration of the unconquered sun for Christmas to match their religious leanings.

The detective Mary and I write about, John the Eunuch, Lord Chamberlain to the sixth century emperor Justinian I, is a secret Mithran. He needs to keep his religious beliefs hidden because the Eastern Roman Empire was officially Christian. Justinian wasn't tolerant of Christians who didn't agree with orthodox views on such matters as the nature of Christ alone pagans.

A historian might quibble over whether a Lord Chamberlain (we use the term Victorian translators used to describe the position) could have been a secret Mithran, but we're writing fiction and it's useful to have a protagonist who's somewhat of an outsider. Besides, our own high officials today get up to all sorts of antics in secret, to judge from the few we find out about.

There's also been doubt expressed as to whether Mithraic religion survived until the sixth century, there being no record of it by then. To which we reply that it was a mystery cult which purposely left no record even during its heyday a few hundred years earlier.

Mostly it is the physical artifacts that survive -- the cave-like underground mithraeums where the followers worshipped and the statuary and bas relief depictions of the God. There were no writings, no recorded liturgy. What little information we have is gleaned from church fathers who mentioned Mithraism to criticize it.

Mithras is usually shown slaying a bull and so bull sacrifices have been postulated to be part of Mithraic ritual, although few surviving mithraeums would have been large enough to accomodate such a ceremony. The mithraeum beneath the grounds of the Great Palace in Constantinople was, however, as rather graphically depicted in One For Sorrow.

We were chided about that scene once, told that the Mithrans had got a bad rap. They weren't so horrid as to kill bulls. That was just a myth. They probably sacificed nothing larger than a chicken. As if chickens don't bleed!

Sacrifices aside, Mithraic virtues such as loyalty, bravery and self sacrifice could pass for Christian. One of our conceits is that John, as a practicing Mithran who takes his religion seriously, acts in a more Christian manner than many of the Christians he encounters -- people who call themselves Christians simply because it is the state religion.

John's elderly, devout servant Peter worries about his employer's soul, but insists, if pressed, that John merely chooses to call the Lord by a different name. Peter believes, as Mary and I do, that a person defines themselves by what the way they live rather than what they say or how loudly they say it.