The subject of the history of the English

A language can be studied synchronically and diachronically. In the synchronic approach a language is regarded as a fixed unchangeable system, while in the diachronic approach every linguistic fact is interpreted as a stage or a step in the never ending evolution of the language. In studying the history of the English Language we consider its phonetics, grammar and word-stock diachronically.
However the diachronic and synchronic approaches can be combined; the development of the language can be presented as a series of cross-sections, e.g. Old English, Middle English and Modern English.