§359. Peculiar Genitives

Peculiar Genitive constructions are the following:—

a. A poetical genitive occurs rarely in exclamations, in imitation of the Greek (Genitive of Exclamation):—

• dī immortālēs,mercimōnīlepidī; (Pl. Most. 912), good heavens! what a charming bargain!
• foederis heu tacitī; (Prop. 4.7.21), alas for the unspoken agreement!

b. The genitive is often used with the ablatives causā, grātiā, for the sake of; ergō, because of; and the indeclinable īnstar, like; also with prīdiē, the day before; postrīdiē, the day after; tenus, as far as:

• honōris causā, with due respect (for the sake of honor).
• verbīgrātiā, for example.
• êius lēgisergō, on account of this law.
• equus īnstar montis (Aen. 2.15), a horse huge as a mountain (the image of a mountain).
• laterum tenus (id. 10.210), as far as the sides.