St. Thomas Aquinas and Latin

Madrid is holding yet another Second-hand Book Fair in Paseo de Recoletos, near Cibeles. I try to visit the stands in order to keep in touch with my literary youth and recollect old books read as a child. Suddenly my eyes discover Emilio Salgari, James O. Curwood, Emile Zola, Rafael Sabatini... and so many others we can no longer find in the few bookstores that are left open.
Yesterday I saw a two-volume set of St. Thomas Aquinas´ Summa Theologica in Latin. The price was 150 euros. The combination of author, title, and language got me to ponder.
150 euros for a title written in a dead language, few can read today, is a hefty sum. St. Thomas Aquinas is no celebrity -he has not appeared on TV recently!- and Latin is not a popular language people are trying to master.
When nationalisms decided to use local languages and do away with Latin, European civilization lost a means of scientific and cultural communication of great importance. Educated people throughout Europe read Latin, and any book written in that language could cross borders and countries.  Latin was a true Lingua Franca.
Alas, Latin is no more. And yet, there are two volumes of the Summa Theologica wating to be bought for a 150 euros at the Feria del Libro Viejo y Antiguo, de Madrid.
I feel both sad and hopeful.