The aim is to make foreign constructions salient and transparent to learners and, in many cases, spare them the technical jargon of grammatical analysis.
It differs from literal translation and interlinear text as used in the past, since it takes the progress learners have made into account and only focuses upon one specific structure at a time.
Although the main intent is satirical rather than didactic, Twain provides interesting insights into the workings of the German language.
Mirroring is amply used in commercial phrasebooks and computer courses and is a common device in scientific grammars of remote languages, but has been ignored by modern coursebook authors, along with other bilingual techniques such as the sandwich technique, presumably because of the mother tongue taboo, still prevailing in mainstream language teaching methodology.
According to Butzkamm & Caldwell,[3] mother tongue mirroring should be re-instated as a central teaching technique, especially when learners are not ready for grammatical analysis.