The tenth poem of Propertius Book 4 is the most remarkable in a collection full of surprises for its readers, and appears to mark a significant departure from his previous work. If Propertius had never written his final book of poetry, we might characterize him on the basis of his earlier books as the quintessential Latin love elegist: he rejects not only a military career, but even the less demanding task of celebrating Augustus' victories, in favour of the love elegist's self-indulgent life of leisure: cf. e.g. Prop. 2.1.39–46. In the first poem of Book 4, however, Propertius announces what appears to be a wholly different poetic programme; in place of the erotic elegies of the previous books is a new ‘serious’ purpose: Propertius will sing about national, religious and antiquarian themes, as the ‘Roman Callimachus’ (Propertius 4.1a.63–4). However, as soon as the next poem, Propertius is commanded to return to his usual theme of obsessive elegiac love for one woman, a topic described as haec tua castra (‘this is your sphere of operations’, 4.1b.135). The poems which follow in Propertius 4 tend to strike a balance between antiquarian seriousness and elegiac frivolity. For example, in 4.4, Propertius relates the Vestal Virgin Tarpeia's betrayal of Rome, connecting several contemporary urban landmarks with the poem's heroine, but he remains true to his earlier colours by presenting Tarpeia as an elegiac lover who falls in love at first sight and betrays her city out of passion.