In 1785 Kant published a series of critical reviews of Johann Gottfried Herder’s Ideas for a Philosophy of the History of Humanity (1784–1785), in which he not only challenges Herder’s conception of nature but also, and more importantly, his methodology. Kant’s complaint is that by relying on analogy, Herder draws deeply mistaken conclusions that overlook fundamental differences between human and nonhuman beings. But was Kant’s critique of Herder entirely fair? And how does it compare to Kant’s own use of analogy? My claim is that Herder’s use of analogy posed a fundamental methodological challenge to Kant, a challenge he sought to meet in the years following the reviews. In so doing, however, Kant found himself in the untenable situation of, on the one hand, granting analogy greater significance, and, on the other, severely restricting its use. By tracing the shifts in Kant’s thought through the lens of analogy, I aim to show that Kant’s transformed understanding of analogy reveals a fundamental tension between his a priori “metaphysics of nature” and empirical science, a tension that fundamentally shaped the philosophies of nature after Kant.