This article examines the various discursive strands converging within the cult of friendship in mid-eighteenth-century German culture. Following Christian Fürchtegott Gellert’s “Vier und zwanzigste Moralische Vorlesung” (Twenty-fourth Moral Lecture), it explores a programme of virtue that no longer follows religious values, but is informed by the enlightened paradigm of reason, and the redeeming of this idea within the framework of interpersonal relationships. The second half of the article investigates the relationship between friendship and the epistolary correspondence culture in the eighteenth century, illuminating the practices and artefacts of friendship communication.