The Aeneid by Virgil Book 6 Page 14

if now that golden bough would show itself to us on the tree in the deep wood! For all things truly – ah, too truly – did the seer say of you, Misenus.” Scarce had he said these words when under his very eyes twin doves, as it chanced, came flying from the sky and lit on the green grass. Then the great hero knew them for his mother’s birds, and prays with joy: “Be my guides, if any way there be, and through the air steer a course into the grove, where the rich bough overshades the fruitful ground!

And you, goddess-mother, fail not my dark hour!” So speaking, he checked his steps, marking what signs they bring, where they direct their course. As eyes could keep them within sight; then, when they came to the jaws of noisome Avernus, they swiftly rise and, dropping through the unclouded