Lingua Philosophica

Lingua philosophica ("the philosophical language") is a very early constructed language invented by George Dalgarno (c. 1626-1687), a Scottish schoolteacher, published by him in his Ars Signorum ("Art of Signs"), a lengthy essay published in 1661 which both attempted to set out the philosophical basis of language, as Dalgarno perceived it, and to sketch (in some detail) a constructed language that would, ideally, represent each idea by a word, related ideas by related words, and be sufficiently rational to train its learners' minds in philosophical rigor.

Whether or not Dalgarno succeeded at this task, his Lingua Philosophica is one of the earliest fully functional constructed languages, and most likely the earliest in Europe. It consists of:

A lengthy list of roots corresponding to what Dalgarno believed to be basic linguistic concepts or ideas.

A much briefer grammatical apparatus (chiefly verbal and adjectival inflexional suffixes) which could be used with these roots.

A long (but still limited) "Lexicon" of Latin words glossed in Lingua Philosophica, often by compounding existing roots

A set of writings, primarily translations, in Lingua Philosophica. These include:

1. A foreword addressed to King Charles II.
2. The Lord's Prayer in Lingua Philosophica.
3. A translation of the first chapter of Genesis.
4. Translations of the first five Psalms.
5. Translations of two short Fables of Æsop.

There are also several example sentences given in the main body of the Ars Signorum.