yelli.

Headword: 
yelli.
Principal English Translation: 

literally, the liver (body organ); a metaphor for one's essence, one's being

Attestations from sources in English: 

iyeliztzin = his being
Robert Haskett and Stephanie Wood's notes from Nahuatl sessions with James Lockhart and subsequent research.

çan çe yn iyeliztzin Enseçia = of just one essence (Document 15, Testament of Domingo Yaotl, July 23, 1580, Culhuacan)
The Testaments of Culhuacan (provisionally modified first edition), S. L. Cline and Miguel León-Portilla, eds. (Los Angeles: UCLA Latin Americana Center Nahuatl Studies Series, No. 1, James Lockhart, Series Editor, 17.

themes: 
Anatomy
Metaphors, Proverbs, Riddles