Wikipedia
Logopandecteision is a 1653 book by Sir Thomas Urquhart, disingenuously detailing his plans for the creation of an artificial language by that name. The book is written in several parts, most notably including a list of the language's 66 unparalleled excellences; the rest is made up of rants against his creditors, the Church of Scotland, and others whose neglect and wrongdoings prevent him from publishing this perfected language. Where the book deals with the plan of Logopandecteision, it recalls his earlier work Eskybalauron.
Urquhart was fond of this kind of very elaborate joke, sometimes so elaborate as to be taken by his contemporaries as in earnest. In this case, it is posterity which mistakes his intention. Under the spelling Logopandekteision extracts are sometimes presented which make it appear that Urquhart seriously undertook the creation of a constructed language.
These extracts are somewhat reminiscent of the teetering taxonomic structures of other philosophical languages, and of the baroque grammar of later projects such as Volapük. He promises twelve parts of speech: each declinable in eleven cases, four numbers, eleven genders (including god, goddess, man, woman, animal, etc.); and conjugable in eleven tenses, seven moods, and four voices.
So far as that his project is possible, if absurd. He goes on to make other promises not so easily fulfilled: that "here is no Language in the world, but for every word thereof, it will afford you another of the same signification, of equal syllables with it, and beginning or ending, or both, with vowels or consonants as it doth"; that "in translating verses of any vernaculary tongue, such as Italian, French, Spanish, Slavonian, Dutch, Irish, English, or whatever it be, it affords you of the same signification, syllable for syllable, and in the closure of each line a rime, as in the original"; that any number, of any magnitude whatsoever, may be expressed in this language by a single word, in fact so concisely that the number of sand-grains required to fill Earth and Heaven would be expressible by two letters; and perhaps most extraordinarily, that his language will translate any idiom in any other language, without any alteration of the literal sense, but fully representing the intention.