I present two of Jacob Klein’s chief discoveries from a perspective of peculiar fascination to me: the enchanting (to me) contemporaneous significance, the astounding prescience, and hence longevity, of his insights. The first insight takes off from an understanding of the lowest segment of the so-called DividedLine in Plato’s Republic. In this lowest segment are located the deficient beings called reflections, shadows, and images, and a type of apprehension associatedwith them called by Klein “image-recognition” (εἰκασία). The second discovery involves a great complex of notions from which I will extract one main element:the analysis of what it means to be a number and what makes possible this kind of being, and, it turns out, all Being.