Learnability and Cognition, first published in 1989, brought together two big topics: how do children learn their mother tongue, and how does the mind represent basic categories of meaning such as space, time, causality, agency, and goals? As Pinker writes in a new preface, "The Secret Life of Verbs," the phenomena and ideas he explored in this book inspired his 2007 bestseller The Stuff of Thought: Language as a Window into Human Nature. These technical discussions, he notes, provide insight not just into language acquisition but into literary metaphor, scientific understanding, political discourse, and even the conceptions of sexuality that go into obscenity.