 The phrase is in a passage in Prometheus Unbound by Percy Bysshe Shelley a drama published in 1820.The Orb of time was introduced previously in Trials and Tribble-ations (airdate November 4, 1996 / S5E6)

The Orb of Time is a time travel device, which is highly restricted in the Federation, but Bajor is not a part of the Federation so it is not against regulations for Major Kira but she does get permission from her commanding officer.The Orb is somehow connected to the Aliens that made the wormhole and part of a religion on Bajor, which connects to the overall plot of Deep Space Nine and the Ben Sisko character.