The essay analyses the notion of ‘purity’ in the early writings of Walter Benjamin, focusing more specifically on three essays written around the crucial year 1921: ‘Critique of Violence’, ‘The Task of the Translator’, and ‘Goethe's Elective Affinities’. In these essays, ‘purity’ appears in the notions of ‘pure means’, ‘pure violence’, ‘pure language’, and, indirectly, the ‘expressionless’. The essay argues, on the one hand, that the ‘purity’ of these concepts is one and the same notion, and, on the other, that it is strongly indebted to, if not a by-product of, Kant's theorisation of the moral act. In order to make this claim, the essay analyses Benjamin's intense engagement with Kant's writings in the 1910s and early 1920s: ‘purity’ is a category strongly connoted within the philosophical tradition in which the young Benjamin moved his first steps, namely Kantian transcendental criticism. The essay argues that the notion of ‘purity’ in Benjamin, though deployed outside and often against Kant's theorisation and that of his followers, and moreover influenced by different and diverse philosophical suggestions, retains a strong Kantian tone, especially in reference to its moral and ethical aspects. Whereas Benjamin rejects Kant's model of cognition based on the ‘purity’ of the universal laws of reason, and thus also Kant's theorisation of purity as simply non empirical and a priori, he models nonetheless his politics and aesthetics around suggestions that arise directly from Kant's theorisation of the moral act and of the sublime, and uses a very Kantian vocabulary of negative determinations construed with the privatives-los and -frei (motiv-frei, zweck-los, gewalt-los, ausdrucks-los, intention-frei, etc). The essay explores thus the connections that link ‘pure means’, ‘pure language’ and ‘pure violence’ to one another and to the Kantian tradition.