text: In a few fortuitous instances, which have been used to verify the method and the model (and probably ultimately inspired it), a literary history exists from as early as a few millennia ago, allowing the descent to be traced in detail. The early daughter languages, and even the proto-language itself, may be attested in surviving texts. For example, Latin is the proto-language of the Romance language family, which includes such modern languages as French, Italian, Portuguese, Romanian, Catalan and Spanish. Likewise, Proto-Norse, the ancestor of the modern Scandinavian languages, is attested, albeit in fragmentary form, in the Elder Futhark. Although there are no very early Indo-Aryan inscriptions, the Indo-Aryan languages of modern India all go back to Vedic Sanskrit (or dialects very closely related to it), which has been preserved in texts accurately handed down by parallel oral and written traditions for many centuries.
  The first person to offer systematic reconstructions of an unattested proto-language was August Schleicher; he did so for Proto-Indo-European in 1861.
  Proto-X vs. Pre-X
  Normally, the term "Proto-X" refers to the last common ancestor of a group of languages, occasionally attested but most commonly reconstructed through the comparative method, as with Proto-Indo-European and Proto-Germanic. An earlier stage of a single language X, reconstructed through the method of internal reconstruction, is termed "Pre-X", as in Pre–Old Japanese. It is also possible to apply internal reconstruction to a proto-language, obtaining a pre-proto-language, such as Pre-Proto-Indo-European.
  Both prefixes are sometimes used for an unattested stage of a language without reference to comparative or internal reconstruction. "Pre-X" is sometimes also used for a postulated substratum, as in the Pre-Indo-European languages believed to have been spoken in Europe and South Asia before the arrival there of Indo-European languages.