Staurogram

[Victor]

The word Chi-Rho is often used to describe field marks on coins that are not actually Chi-Rho’s…I have done this more than once. This happens most with the SALVS REIPVBLICAE type issued for Valentinian II, Theodosius I, Honorius, Arcadius and Theodosius II. What is really on the reverse in the left field is a Staurogram (which means monogram of the cross). It is made by superimposing a Tau (T) on a Rho (P) and is also called a Tau-Rho.

The first image below is one I found on the web that shows three monograms that are very similar- Left to right: The 'staurogram' combining the Greek letters Tau and Rho, the Chi-Rho monogram formed by the first two letters in "Christ", and the Iota-Chi monogram composed of the initials for "Jesus Christ."

[Valentinian]

"What is really on the reverse in the left field is a Staurogram (which means monogram of the cross). It is made by superimposing a Tau (T) on a Rho (P) and is also called a Tau-Rho." 

I have chosen to call it a cross-rho. I never thought it had any connection to tau but was a Christian cross.

[Victor]

here is more on the tau-rho from wikipedia, that has some relevant historical references.

https://en.wikipedia.org/wiki/Staurogram

[Valentinian]

Victor, that wikipedia reference on "staurogram" is very helpful. It says "Ephrem says that the Tau represents the cross of Jesus" and gives other reasons for that shape being a "tau-rho". That article seems so scholarly it must be right.

Nevertheless, I am having hard time thinking a T shape within a manuscript must be a tau when it is intended to represent a cross. It could be a cross, not used as a tau, but called a tau for the coincidence of shape. (I am distinguishing between a shape and the its language function as a letter.)

Wikipedia says, "The staurogram was first used to abbreviate stauros (σταυρός), the Greek word for cross in very early New Testament manuscripts such as P66, P45 and P75."  "Abbreviate" seems an odd word here. How does "tau-rho" abbreviate "σταυρός"?  Most abbreviations begin with the first letter of the abbreviated word.

The shape as on the OP coin could easily be interpreted as a cross (including an upward projection above the T shape) - rho. No need for a tau. Then, what would the "P" (rho) be? From wikipewdia, "used as a monogramma Christi alongside the Chi-Rho and other variants, spreading to Western Europe in the 5th and 6th centuries."   Could it be that the X shape was simply replaced with a cross shape and the P (rho) immobilized? I thought about writing "In the West, the Greek "X" for "chi" for the "Ch" in Christ would not be so meaningful, but the cross would be," and then I thought the evidence of the coins was that it was used in the East alongside the chi-rho, so it is not just a western phenomenon (the coins below is from Cyzicus). 

Once again, with the quote continued longer, "Ephrem says that the Tau represents the cross of Jesus (prefigured by the outstretched hands of Moses in Exodus 17:11)." It a standing figure stretches out his hands [to the side] there is a projection (the head) above the horizontal. That would be like a cross with an upward projection, not a T (tau).  I wonder if Ephrem really said the shape represents the cross of Jesus and somehow (earlier or later?) the shape was named tau-rho for the coincidence of shape but not with any real connection to tau (the letter)?  If so, calling it a cross-rho would be appropriate.

Any further musings on this would be welcome.

[Victor]

the shape was named tau-rho for the coincidence of shape but not with any real connection to tau (the letter)?  If so, calling it a cross-rho would be appropriate.

Any further musings on this would be welcome.

Here is more on why it is called a tau-rho

 â€œIn Greek, the language of the early church, the capital tau, or T, looks pretty much like our T. The capital rho, or R, however, is written like our P. If you superimpose the two letters, it looks something like this . The earliest Christian uses of this tau-rho combination make up what is known as a staurogram. In Greek the verb to ‘crucify’ is stauroō; a ‘cross’ is a stauros … [these letters produce] a pictographic representation of a crucified figure hanging on a cross—used in the Greek words for ‘crucify’ and ‘cross."

https://www.biblicalarchaeology.org/daily/biblical-topics/crucifixion/the-staurogram/

[Valentinian]

"staurogram. In Greek the verb to ‘crucify’ is stauroō; a ‘cross’ is a stauros … [these letters produce] a pictographic representation of a crucified figure hanging on a cross"

Agreed. Although, this has nothing to do with a tau (as a letter, only a shape). The argument (and the word staurogram) acknowledges it is a cross shape. It is not the letter tau the way the X is a chi-rho really is an X (chi). I can go with staurogram because it is an accepted term. But "tau-rho" does not seem to me as justified. Maybe it has acceptance because it is parallel with "chi-rho". But "cross-rho" is what it looks like and is easy to understand.

[Victor]

except the word "cross-rho" is confusing and not in keeping with traditional usage such as chi-rho or tau-rho which are both combinations of Greek. If tau-rho does not seem right, then staurogram is best, or if you want to use the word cross -- monogrammatic cross.

It is not the letter tau the way the X is a chi-rho really is an X (chi)

but the tau-rho is made with a tau (T) and a rho (P)