Prayer to Mars Gradivus

The oak with the Golden Fleece stands in the grove of Ares, and Mars is called on to guard it.

Excubias, Gradive, tene — keep watch, Gradivus. Excubiae is a word from army life: the night guard, the turn of duty at a post. The god is not prayed to, he is detailed. And he is named in military terms: Gradivus, from gradior, "the marching one" — Mars on the move; an epithet made for a sentry.

The protection ordered is acoustic. Praesentia luco arma tubaeque sonent, vox et tua noctibus exstet — let your present arms and trumpets sound in the grove, and let your voice stand out at night. The god is asked not to be seen but to be heard: clatter, trumpets, a voice in the dark. The safeguard is designed as an alarm system, calculated to make a thief leave of his own accord without meeting anyone.

Praesentia … arma — arms present, manifest. In cult language praesens means "acting here and now" (cf. diana-023); here it is said of the weapons rather than of the god, and the weapons turn out to be the part of him that has to be on the spot.