This thesis considers how Martin Heidegger treats “wonder” (thaumazein) in Plato and Aristotle versus how it appears to be treated by them. The introduction outlines how the problem of wonder arises when Heidegger mentions particular instances from Plato’s Theaetetus and Aristotle’s Metaphysics as the basis for his claim that philosophy originates in wonder. In chapter one, I analyze each of the twenty-four occurrences of wonder in Plato’s Theaetetus, beginning with a preliminary discussion of Heidegger’s delimitation of wonder from the wondrous. In chapter two, I examine the relation between philosophy and wonder in chapters one and two of Book Alpha of Aristotle’s Metaphysics. In chapter three, I begin by considering Heidegger’s later lecture, What is that—Philosophy?, before turning to his earlier writing, The Need and Necessity of the First Beginning and the Need and Necessity of an Other Way to Question and to Begin. I end by reflecting on Heidegger’s account of pre-Socratic versus Socratic philosophy in these writings and consider how Leo Strauss seems to provide an alternative to Heidegger’s analysis. Finally, in the conclusion, I discuss the relation between wonder and Eros in Plato and Aristotle. / 1 / Ryan Patrick Crowley