Pilobolus is performing two programs during its three-weeks at the Joyce Theater this summer, and each piece is unique while being ineffably consistent with the style of the company. It is dance in the broadest sense of the word, rhythmic movement. Yet, the company borrows from gymnastics and acrobatics, and sometimes, the closest parallel one can find is the Moscow Circus in the old Soviet Union. The five pieces in program A are distinct and appeal to both dance mavens and neophytes. “On the Nature of Things” is a classical study in movement. Nathaniel Buchsbaum, Krystal Butler and Quincy Ellis