Motherese is not grammatically simple. That impression is an illusion; grammar is so instinctive thatwe do not appreciate which constructions are complex, until we try to work out the rules behindthem. Motherese is riddled with questions containing who, what, and where, which are among themost complicated constructions in English

The three-year-old, then, is a grammatical genius – master of the most constructions, obeying rulesfar more often than flouting them, respecting language universals, erring in sensible, adult like ways,and avoiding many kinds of errors altogether

At the time of the publication of Aspects of the Theory of Syntax it seemed that all of the semantically relevant parts of the sentence, all the things that determine its meaning, were contained in the deep structure of the sentence. The examples we mentioned above fit in nicely with this view. “I like her cooking” has different meanings because it has different deep structures though only one surface structure; “The boy will read the book” and “The book will be read by the boy” have different surface structures, but one and the same deep structure, hence they have the same meaning.

the aims become more ambitious: to explain all of the linguistic relationships between the sound system and the meaning system of the language