The dating of Manilius' Astronomica and of the Aratea attributed to Germanicus are both long-standing problems of Latin scholarship. The large number of significant correspondences between the two poems suggests a considerable degree of imitation and allusion one way or the other, but it is widely agreed that the internal evidence of the poems can shed no light on the direction of the influence. I would like to present a new observation, however, suggesting that the Aratea was already available to (...) Manilius in some form by the time he came to compose his first book. (shrink)