Sunlight is constant and is undeviating. Similarly the universal mind is constant and absolute in its purpose: virtue. Marcus mentions this previously in book 6, passage 17.
Our actions and intent, too, should be direct and unrelenting in right actions. We can be the light a world that needs it - in a world that needs love, kindness, courage, temperance and wisdom. Our justice should be merciful and we can infuse teaching and correction in our quest to deliver consequences of wrong-doing. Truly there is universal light in all, and we can do our part to bring that light out in others. Like the sun, we can be the beacon of hope, warmth, enlightenment and wisdom.
(see also Citadel p. 241, 270