The Upanishads, Part 1 (SBE01), by Max Müller, [1879], at sacred-texts.com

SEVENTH KHANDA.

1. 'The altar is man, O Gautama; its fuel speech itself, the smoke the breath, the light the tongue, the coals the eye, the sparks the ear.

2. 'On that altar the Devas (prânas) offer food. From that oblation rises seed.