"I've a fair knowledge of the modern tongue, and a rather unusual command of Arabic.

The modern Persian, as you know, comes straight through from the speech of Xerxes, of Cyrus, of Darius whom Alexander of Macedon conquered.

It has been changed mainly by taking on a load of Arabic words.

Well--there wasn't a trace of the Arabic in the tongue they were speaking.
"It sounded odd, of course--but I could understand quite easily.

They were talking about Ruth.