This spirit in (my) heart is that mind-making, breath-bodied, light-formed, truth-thoughted, ether-spirited One, of whom are all works, all desires, all smells, and all tastes; who comprehends the universe, who speaks not and is not moved; smaller than a rice-corn, smaller than a mustard-seed, ...

greater than earth, greater than heaven.

This (universal being) is my ego, spirit, and is _brahma,_ force (absolute being).

After death I shall enter into him (3.14).[8] This all is breath (==spirit in 3.15.4).
After this epitome of pantheism follows a ritualistic bit: Man is sacrifice.

Four and twenty years are the morning libation; the next four and forty, the mid-day libation; the next eight and forty, the evening libation.