'This is a closely argued, very substantive piece of work with interesting broader implications for syntax and semantics and the general nature of language structure. I think it is a very serious contribution.' -- Noam Chomsky, M.I.T. How do humans acquire, at a very early age and from fragmentary and haphazard data, the complex patterns of their native language? This is the logical problem of language acquisition, and it is the question that directs the search for an innate universal grammar. As Time Goes By extends the search by proposing a theory of natural-language tense that will be responsive to the problem of language acquisition. The clearly written discussion proceeds step-by-step from simple observations and principles to far-reaching conclusions involving complex data carefully selected and persuasively presented.