Dionysus: "There they sit among the rocks, under the silvery pines-- a congregation in the open." (1)
It's significant that Dionysus drove all the women of Thebes out into the woods to celebrate his greatness. One of the central themes of the play is the tension that exists between the city of man and the natural world. Dionysus represents wild, untamed nature, so of course he'd drag the ladies out into the woods for his rituals.
Chorus: "O Thebes, Semele's nurse Put ivies round your turrets, break forth in green" (3)
Did you catch the symbolism here? The Chorus invokes the image of the stone walls of Thebes being decked with greenery. It could be seen as symbolic of the relationship of man with the natural world – man being the city, nature being the ivy. Here, early in the play, the image is harmonious. Perhaps, the Chorus is still hopeful that Dionysus can bring Thebes around to his way of thinking without violence.
Dionysus: "Touch off the thunderbolt's sizzle of light. Burn down, oh burn down the palace of Pentheus." (93)
Now nature is not being so friendly too the those who oppose Dionysus. Whereas before we got images of nature and man in harmony, now we see nature as fearful tool of punishment. Primal nature, like Dionysus, can be both a creative and destructive force in the lives of human beings.
Pentheus: "Ring the city round. Seal off every outlet. That's an order." Dionysus: "Whatever for? Can gods not somersault over walls?" (111-112)
Dionysus points out that the gods can't be contained by the man-made city. This could be seen as symbolic of the helplessness of man in the face of nature. The gods themselves represent the untamed primal forces, while the city represents the machinations of mankind.
Herdsman: "Some [Maenads] fondled young gazelles or untamed wolf cubs in their arms and fed them with their own milk." (119)
Some of the women possessed by Dionysus have apparently taken to breast feeding baby animals. Kind of a strange hobby, we guess, but it's also another image of human beings and nature in harmony. The union of the Maenads and these young creatures can be seen as an intimate and holy thing.
Herdsman: "Anyone who fancied liquid white to drink just scratched the soil with fingertips and got herself a jet of milk" (119)
Here we have the reverse of the previous image of the Maenads breast feeding young animals. Whereas before we saw the women nurturing nature, now we see nature nurturing the women. The possibility of true union between humanity and the natural world is shown in these complementary images.
Chorus: "[…] a fawn at play in the green Joy of a meadow, escaped from the […] net […] of the hallowing huntsman." (171)
You can find the motif of hunting throughout The Bacchae. It falls right into the whole man vs. nature thing, right? Humans go out into nature to shoot things and eat them. Seems pretty straightforward. This particular shout out to hunting is pretty interesting though, because it could be alluding to Pentheus who is about to get snared in Dionysus's trap. It's kind of a reversal, because throughout the play Pentheus is the main representative of the world of man, and now he'll be hunted like an animal.
Agave: "Without a trap I trapped him: This tenderest whelp of a lion." […] Chorus: "He looks like a beast of the wild with his hair." (231-246)
Throughout the play the line between man and animal is blurred. Dionysus appears in both forms, the Maenads are constantly described as animal-like, and here Agave has mistaken her own son for a lion, ripping him apart. This blurring could be seen as a way of showing that human beings are a lot more like animals than we'd like to admit, that we're not as removed from the natural world as we pretend to be.
Chorus: "Great Dionysus, breaker of barriers Son of the Father imperial; Vine-clad god and priest of the natural" (308)
The Chorus celebrates Dionysus as a champion of the natural world. They highlight how he is a being that blurs the line between man and nature, bringing the opposing forces together. Sometimes this union is violent and sometimes peaceful. Whatever it takes, Dionysus seems bent on reminding humanity of its roots.
"O Bacchus, bind us with bryony, Crown us with ivy, and Let every peak of Cithaeron ring With the triumph of animal holiness." (309)
The Chorus prays to Dionysus to bind them with nature. They long for union with both the god and the wild animal forces he represents. We would ask, at what point can this be taken too far? If all of humanity through itself headlong into animalistic practices, wouldn't we lose what it is to be human? How do we find a balance between the two forces?