It is the coming down of the first Avatar to wake up the earth to Consciousness — that is, to bring an intensity of Consciousness and Realisation in this inconscient world.
Sri Aurobindo describes how the message sent from the Supreme to repair the harm done as by a kind of imperative influence waken up again the Consciousness to begin to climb up, back to the Supreme Consciousness.
About Savitri | B1C1-08 Memory of Past Attempts (p.4)