Dating from 1234 CE, the astronomical treatise Ris?la-yi Mu??n?ya is among the earliest works composed by its illustrious author Khwaja Na??r al-D?n T?u?s? (d. 1274 CE). T?u?s? appears to have completed this work shortly after gaining the patronage of the mu?tasham N??ir al-D?n, the Ism???l? governor of Quhistan, and he dedicates this work to the governor’s son. Subsequently, T?u?s? composed many of his most well-known works while enjoying Ism???l? patronage in Quhistan as well was in Daylaman, the seat of Ism???l? power. The seismic events surrounding the defeat of the Ism???l?s in 1256 CE and the extirpation of the storied Abbasid empire at the hand of Hülegü Khan in 1258 CE were to force T?u?s? to switch political and personal allegiances, however, and have left indelible traces in his scholarly output, as well. The most well-known of these traces are T?u?s?’s revisions to the foreword and epilogue of his celebrated work on ethics, Akhl?q-i N??ir? (which was also composed early in T?u?s?’s career, postdating Ris?la-yi Mu??n?ya by a year). The foreword in Ris?la-yi Mu??n?ya show great affinity to that of Akhlaq-i N??ir? in its rhetorical devices and in the distinctly florid Persian in which T?u?s? praises his Ism???l? patrons. Like that of Akhl?q -i N??ir? the revised foreword to Ris?la-yi Mu??n?ya consists of a more sober text, penned with a view to T?u?s?’s role as Ilkhanid courtier and adviser to Hülegü. However, the revised foreword in Ris?la-yi Mu??n?ya diverges from that of its more well-known successor, Akhl?q-i N??ir?, in that T?u?s? does not include an explicit renunciation of the Ism???l?s and of his long-term affiliation with the Ism???l? court. Also notable is the fact that the original epilogue for Ris?la-yi Mu??n?ya appears as virtually intact in many of the surviving manuscript copies, raising questions regarding the history of Ris?la-yi Mu??n?ya and the importance afforded to it by the author. This paper contrasts the fate of T?u?s?’s early work on astronomy with that of Akhl?q-i N??ir?, with regard to the evolving ideological outlook of T?u?s? and the political realities of his career.