Greimas proposed an original method for "discourse semiotics" that evolved over a thirty-year period. His starting point began with a profound dissatisfaction with the structural linguistics of the mid-century that studied only phonemes (minimal sound units of every language) and morphemes (grammatical units that occur in the combination of phonemes). These grammatical units could generate an infinite number of sentences, the sentence remaining the largest unit of analysis. Such a molecular model did not permit the analysis of units beyond the sentence.