Full Idea
The Principle of Noncontradiction is for Aristotle the ultimate regulator of predication. In order for any predication to be significant it must refer to something definite and stable.
Gist of Idea
For Aristotle predication is regulated by Non-Contradiction, because underlying stability is essential
Source
comment on Aristotle (Metaphysics [c.324 BCE], 1011b13) by David Roochnik - The Tragedy of Reason p.152
Book Reference
Roochnik,David: 'The Tragedy of Reason: the Platonic logos' [Routledge 1990], p.152