All this is Brahman (n.) Let a man meditate on that (visible world) as beginning, ending, and breathing in it (the Brahman). Now man is a creature of will. According to what his will is in this world, so will he be when he has departed this life. Let him therefore have this will and belief:

In plain words: Everything is Brahman, the ultimate reality: all things come from it, end in it and live by it. A person is shaped by what they deeply want and believe. What you set your heart on in this life decides what you become after death. So set your heart on the truth described next.