Source: Jacob Neusner's Judaism: The Evidence of the Mishnah, page 282.
"The Mishnah's evidence presents a Judaism which at its foundations and through all of its parts deals with a single fundamental question: What can a man do? The evidence of the Mishnah points to a Judaism which answers the question simply: Man, like God, makes the world work. If man wills it, nothing is impossible. When man wills it, all things fall subject to that web of intangible status and incorporeal reality, with a right place for all things, each after its own kind, all bearing their proper names, described by the simple word, sanctification. The world is inert and neutral. Man by his will and word initiates the processes which force things to find their rightful place on one side or the other of the frontier, the definitive category, holiness. That is the substance of the Judaism of the Mishnah."
The Mishnah is about organizing the creation according to what God wants, yet Neusner points out that the individual Jew has some autonomy in what he declares holy and unholy. Is this a contradiction? Can human autonomy contradict God's will?
At the same time, the priest had a certain degree of autonomy in the Hebrew Bible, meaning that his declarations made a person or thing clean or unclean.