What is the je-ne-sais-quoi, if it is indeed something at all, and how can it be put into words? In addressing these questions, Richard Scholar offers the first full-length study of the je-ne-sais-quoi and its fortunes in early modern Europe. He examines the expression's rise and fall as a noun and as a topic of philosophical and literary debate, its cluster of meanings, and the scattered traces of its "pre-history." Placing major writers of the period such as Montaigne, Shakespeare, Descartes, Corneille, and Pascal alongside some of their lesser-known contemporaries, Scholar argues that the je-ne-sais-quoi serves above all to trace a series of first-person encounters with a certain something as difficult to explain as its effects are intense, and which can be expressed only by being expressed differently. He shows how the je-ne-sais-quoi comes to express that certain something in the early modern period, and suggests that it remains capable of doing so today.