The idea of a universal second language is not new, and constructed languages are not a recent phenomenon. The first known constructed language was Lingua Ignota, created in the 12th century. But the idea did not catch on in large numbers until the language Volapük was created in 1879. Volapük was popular for some time and apparently had a few thousand users, but was later eclipsed by the popularity of Esperanto, which arose in 1887. Several other languages such as Latino sine Flexione and Idiom Neutral had also been put forward. It was during this time that French mathematician Louis Couturat formed the "Delegation for the Adoption of an International Auxiliary Language".