Lo, the darting bowling orb! Lo, the brother orbs around, all the clustering suns and planets, All the dazzling days, all the mystic nights with dreams, Pioneers! O pioneers! (73-76)
Here our speaker's rapturous admiration extends to the cosmos, the sun and stars, days and nights. There's a connection, maybe, between the capacity to be full of wonder at the cosmos and the ability or desire to venture forth into the unknown.