It was exactly 100 years ago, in 1920, that the Constructivist artist Naum Gabo and his brother Antoine Pevsner issued their “Realistic Manifesto,” a statement on the subject of modernity. It declared that to be authentic, modern art must reflect the “kinetic rhythms” of the modern age. Gabo’s work certainly did. His immaculate sculptures were characterized by their sleek dynamism. One hundred years later—to celebrate the “Realistic Manifesto” and its vision—Gabo’s sculptures, paintings, drawings, and designs are on view in the U.K. for the first time in 30 years. —E.C.