Jaiminīya (Talavakāra) Brāhmaṇa 1.18

For he goes to heaven. He says to him: 'Who you are, that am I; who I am, that are you. Come!' He enters into this very essence of good deeds. His sons enter upon his inheritance, the ancestors upon his good deeds. He who knows thus has two selves and two inheritances. He who offers the fire-offering without knowing this has only one self and one inheritance.

Speech, indeed, is the milch-cow of the fire-offering.

Her calf is the mind.

With the mind, indeed, they milk speech when she has yielded.

With the calf, indeed, they milk the mother when she has yielded.

For the mind goes first, and speech follows behind; therefore, as the calf goes first, the mother follows behind.

The heart is the tethering-post, the breath is the rope.