The language Interlingue, known as Occidental until 1949, is a planned international auxiliary language created by Edgar de Wahl, a Balto-German naval officer and teacher from Tallinn and published in 1922. The vocabulary is based on existing words from various languages and a system of derivation using recognized prefixes and suffixes; the language is thereby naturalistic, at the same time. Occidental was quite popular in the years up to, shortly after the Second World War, but declined thereafter. Occidental is devised so that many of its derived word forms reflect the forms common to a number of Western European languages those in the Romance family, along with a certain amount of Germanic vocabulary. Words were formed through application of de Wahl's rule, a set of rules for regular conversion of verb infinitives into derived nouns and adjectives including double-stem verbs of Latin origin; the result is a language easy to understand at first sight for individuals acquainted with several Western European languages.
This readability and simplified grammar along with the regular appearance of the magazine Cosmoglotta made Occidental popular in Europe during the 15 years before World War II. In The Esperanto Book, Don Harlow says that Occidental had an intentional emphasis on European forms, that some of its leading followers espoused a Eurocentric philosophy, which may have hindered its spread. Still, Occidental gained adherents in many nations including Asian nations. Occidental survived World War II, undergoing a name change to Interlingue, but faded into insignificance following the appearance in 1951 of a competing naturalistic project, which attracted among others the notable Occidentalist Ric Berger; the emergence of Interlingua occurred around the same time that Edgar de Wahl, who had opted to remain in Tallinn, was sent to a sanitarium by Soviet authorities and was not permitted to correspond with Occidentalists in Western Europe. His death was confirmed in 1948; the proposal to change the name from Occidental to Interlingue was twofold: to attempt to demonstrate to the Soviet Union the neutrality of the language, in hopes of a union with Interlingua.
The activities of Occidental and its users can be seen through the magazine Cosmoglotta, which began publication in February 1922 in Tallinn, Estonia under the name Kosmoglott. The language announced that year was a product of years of personal experimentation by de Wahl under the name Auli, which he used during the period from 1906 to 1921 and on gained the nickname proto-Occidental. During the development of the language de Wahl explained his approach in a letter to an acquaintance the Baron d'Orczy written in Auli: "My direction in the creation of a universal language seems quite regressive to you... I understand that quite well. I do not begin with the alphabet and the grammar and have to adopt the vocabulary to it, but just the other way around: I take all international material of words, endings, grammatical forms etc. and I work to organize that material, put it in order, interpolate and sift through it." During the development of Occidental through Auli, de Wahl corresponded with the Italian mathematician and creator of Latino sine flexione Giuseppe Peano and gained an appreciation for the international vocabulary in that language, writing that "I believe the "Vocabulario commune" book by Professor Peano to be a more valuable and scientific work than the entire scholastic litterature of Ido on imaginary things evoked by the "fundamento" of Zamenhof."
Occidental was announced in 1922 at a stage of near but not total completion. De Wahl did not intend to announce the language for another few years but did so through the publication of Kosmoglott and the name Occidental for the language after hearing that the League of Nations had begun an inquiry into the question of an international auxiliary language, it began gathering followers despite a complete lack of grammars and dictionaries due to its readability. Two years de Wahl wrote that he was in correspondence with some 30 people "in good Occidental" despite the lack of learning material; the first dictionary was published the next year in 1925, the radicarium directiv, a collection of Occidental root words and their equivalents in 8 languages. For a number of years Kosmoglott was a forum for various other planned languages, while still written in Occidental; until 1924 the magazine was affiliated with the Academia pro Interlingua, which promoted Peano's Latino sine flexione. In 1927 the name was changed to Cosmoglotta as it began to promote Occidental in lieu of other languages, in January of the same year the magazine's editorial and administrative office was moved to Vienna, Austria in the region of Mauer, now part of Liesing.
Much of the early success for Occidental in this period came from the office's new central location, along with the efforts of Engelbert Pigal from Austria, whose article Li Ovre de Edgar de Wahl led to interest in Occidental from users of the Ianguage Ido. Besides the new location in a city much closer to the centre of Europe, the Vienna period was marked by financial stability for the first time due to the support given by a number of backers Hans Hörbiger from Vienna, G. A. Moore from London, from which "Cosmoglotta was able to live without difficulty and gained a circle of readers despite the economic crisis". Hörbiger and Moore died at "nearly the same time" in 1931, Cosmoglotta was again forced to rely on revenue from subscriptions, publications and th