Allow me to doubt that. I'm reasonably well read, and have been interested in history since I was a wee one, and I have never read a single line of either Durant, Will and Ariel, in my life. The only reason why I know who Will Durant was is that I lived in Los Angeles for three months in the 1990s. I just checked, and some of their books were translated into German, but not with one exception by big publishers. And I don't think the German situation is atypical for the Durants in non-English-speaking countries. I can't recall seeing any Durant work in a French bookstore when I visited France, and as a Canadian, he'd have had an advantage there. (BTW, not that I doubt he was translated into French - just not that it reached such a wide audience.) French wiki says the sale of Durant books world wide as of this article is 17 million books, which given there are Indian cities with more inhabitants is really not that much. How are the Spanish translations faring? Are there any in Mandarin or Cantonese? Arabic? In print, today?

Now, I have no doubt Durant outsold, say, Thomas Carlyle or Macauly. Easily. And that in English speaking countries, he was more widely read. But in countries where English is not the primary language?

Re: Dead end - did you check Valory's memoirs for "Césarion", just to be absolutely sure?