Ian Ayres, professor at Yale Law School, walks through Clark v. West as part of his American Contract Law course, originally recorded for Coursera. The case turns on a publishing contract in which an author's compliance with a sobriety condition affected his royalty rate, and Ayres uses it to examine when courts will excuse a party from a contractual condition rather than enforce it strictly. He traces the reasoning judges use to distinguish conditions from promises and explains why waiver and forfeiture concerns can lead courts to relax literal contract terms. The lecture is part of a numbered series covering contract performance doctrine, building on earlier sessions about conditions precedent. Ayres keeps the focus tight on the case text and its holding, treating it as a vehicle for the broader doctrinal point about when strict compliance can be excused.