Modern grammar is basically a deliberate contrast with traditional grammar. It's related to, but different from, the difference between prescriptive and descriptive grammar. In the case of English, traditional grammar is ultimately Latin-based, because the first scholars understood Latin grammar and applied its principles to English. This worked fairly well, but only up to a point. Both are Indo-European but Latin is a romance language, while English is Germanic. Application of Latin rules also resulted in strange rules like "a preposition magically transforms into an adverb when it has no...