The text behind the portrait is in Bulgarian, not in Russian. Tolstoy never wrote in Bulgarian. He wrote in Russian only. These two languages (Russian and Bulgarian) are very different: Bulgarian speakers cannot understand Russians. Yes, the alphabets are similar, but the languages are not. Bulgaria is: [link]
I think it is just a quote made to be read by Bulgarians. Could've been English as well if the artist was from an English speaking country. Other than that, thanks for making this known to people since they often think Bulgaria and Russia are the same thing.