Interlinguistics of interlinguistics are, however, not so constructive, but rather descriptive, comparative, historic, sociolinguistic, or concerned with translation by humans or machines. As for Esperanto, which is the most widely used constructed interlanguage, there is a relatively abundant literature about the language itself and its philology (see Esperantology). Only a few of the many constructed languages have been applied practically to any noteworthy extent. The most prosperous were Volapük (1879, Johann Martin Schleyer), Esperanto (1887 Ludwik Lejzer Zamenhof), Latino sine flexione (1903, Giuseppe Peano), Ido (1907, Louis Couturat), Occidental-Interlingue (1922, Edgar de Wahl) and Interlingua (1951, IALA and Alexander Gode), with
Justus Ludwik Decjusz by the "Stowarzyszenie Willa Decjusza" (Organization Decjusz's Villa), which is located in the building. Justus Ludwik Decjusz Justus Ludwik Decjusz (, ; 1485–1545) was a notable Polish burgher and diplomat of German origin in 16th-century Kraków. He served as a finance minister and secretary to the Polish king Sigismund I the Old. Originally from Alsace, Decjusz's career peaked with his appointment as the king's personal adviser and overseer of the royal mint. He was also the author of a widely circulated text "De vetustatibus Polonorum" (, "On the Ancient Origins of the Poles"), an early version of the Sarmatian myth