The association between J. Robert Oppenheimer and the famous verse from the Bhagavadgītā - "Now I am become Death, the destroyer of worlds" recalled in a 1965 interview - has become, in the collective imagery, the emblem of the scientist's tragic consciousness in the post-atomic era. Oppenheimer's knowledge of the Indian text, however, dates back more than thirty years earlier and is rooted in his years at the University of California, Berkeley. This paper examines a letter addressed to his brother Frank on 12 March 1932, in which Oppenheimer reflects on the "virtue of discipline" as a metaphysical question, drawing on a wide range of intellectual traditions - from the Bhagavadgītā to Stoicism, from Thomas Aquinas to Spinoza - to explore the relationship between knowledge and professional vocation. A textual and historical analysis of this document, including the identification and examination of key terms, shows that already at this stage Oppenheimer had developed a conception of scientific practice grounded in a literary and religious universe, in which the Bhagavadgītā stands out as a privileged point of reference. In the latter part of the letter, Oppenheimer develops concepts drawn from the Gītā - such as discipline, detachment, and peace - suggesting that the text played a significant role in his personal reflection and in his understanding of scientific vocation. The textual analysis of the letter, together with the reconstruction of its historical and biographical context, makes it possible to identify the 1932 reference to the Bhagavadgītā as a significant precedent for the well-known quotation of 1965, one of the earliest traces of an intellectual interest that would persist and resurface in the later stages of the scientist's public life.