What is Animus Hominis Est Anima Scripti?

Legal Definition
The intention of the party is the soul of the Instrument. 3 Bulst. 07; Fitm. Prin. & Sur. 2G. In order to give life or effect to an instrument, it is essential to look to the intention of the individual who executed it
Legal Definition
The intention of a man is the spirit of his writing.
-- Ballentine's Law Dictionary