"Think." EP. The single off of the EP "She", which features The Rhapsodist, explores the lives of three women who are all lost in different ways-physically, mentally, and spiritually. All beats were produced by Mustafa M. Eisa. Proof Theory is a Bay Area hip hop duo that formed in the summer of 2011 in Walnut Creek, California. Conscious lyrics and jazzy beats highlight their unique style. The members, Mustafa M. Eisa (producer, author, vocalist) and Classified Flow (author, vocalist), debuted with their single, "The City" Facebook: /classifiedflow /prooftheory