There are two periods in the development of transformational grammar: Transformational Grammar and Transformational Generative Grammar.
Transformational grammar (Zelic Harris, Charles Hockett) distinguishes kernels and transformational rules for expansion and rearrangement of kernels. Kernels are simple naked sentences: The sun shines; She is beautiful; I have a car; I read a book; There is a book on the table, etc. All possible sentences are derived from kernels
Transformational Generative Grammar is primarily associated with the name of N. Chomsky, USA, 1928 , linguist, philosopher and intellectualist, professor of Massachusetts Institute of Technology (MIT). Chomsky holds that humans are equipped at birth with innate language faculty to acquire language, which is a specific neurological system. Babies easily develop speech. These are rules that govern sequencing sounds into words and words into sentences. He initiated the shift from behaviorism and empiricism that dominated American linguistics to investigation into language and universal grammar. He criticized behaviorists. According to him, language is not a form of behavior. Generative grammar derives a surface structure from an abstract deep (underlying) structure. Surface are observable structures, deep are underlying structures, they are logical structures of our brain – subject and predicate structures.
Harris and Chomsky developed ideas of transformation in different contexts and for different purposes. For Harris transformation relates to surface structure sentence forms: Jim drinks beer => Beer is drunk by Jim. This transformation relates both structures, passive and active. For Chomsky transformation is a device to transform a deep structure into a surface structure, to show the generation of infinite living structures out of a finite set of deep structures ( I have a car. She is nice.., etc,). The theory of deep structures can serve as a method of analyzing and explaining the generation of surface structures. He married young is a surface structure with a double predicate, the nature of which can be explained transformationally =>He marries and =>He is young. The sentence with a simple nominal predicate can be analyzed as comprising two deep structures : She a beauty?! => She is a beauty. =>It is not true.