He is, as it were, a law of compensation to all things.
The Yellow Emperor travelled to the north of the Red Lake and ascended the K'un-lun Mountains. Returning south he lost his magic pearl.
His spiritual part, his soul.
He employed Intelligence to find it, but without success. He employed Sight to find it, but without success. He employed Speech
Also explained as "Strength."
to find it, but without success. Finally, he employed Nothing, and Nothing got it.
He did not employ Nothing to find it. He only employed Nothing.
"Strange indeed," quoth the Emperor, "that Nothing should have been able to get it!"
Knowledge, sight, and speech, tend to obscure rather than illuminate the spiritual nature of man. Only in a state of negation can true spirituality be found.