Constraints on the art and craft of constructing languages Lessons learnt from Classic interlinguistics

In the 21st century, constructed languages started to be normalized as an object of scientific study. Their construction has become increasingly popular thanks to the spread of the internet and, therefore, the availability of linguistic resources from the most ‘exotic’ human languages. The practice of constructing languages (in brief, conlanging) is often made by non-professional linguists with much enthusiasm and anecdotal experience but without a solid linguistic ground. Interlinguistics may be divided into four periods (preclassic, classic, modern, postmodern), where conlanging is the postmodern part. From its history, contemporary conlangers can profit from the errors and successes of their predecessors of classic Interlinguistics. This period started with the publication of Volapük (1879) until the release by IALA of Interlingua (1951). Its protagonists were mainly involved in the quest for the optimal International Auxiliary Language (IAL); nonetheless, their lessons are still valid.