David Smith devoted his career to the exploration of sculptural form through the medium of steel. He admired the material not only for its durability and industrial strength, but also for the beauty of its reflective surface and its responsiveness to burnishing.

 Two Circle Sentinel exhibits the mastery and delicacy Smith brought to his later steel constructions. The image of the sentinel, or watcher, was a theme that fascinated Smith. He made his first Sentinel sculpture in 1956, and by the end of that decade he had created five works in the first series. In 1961 he produced four additional Sentinel sculptures, all of which are characterized by flat planes of highly burnished stainless steel. With these works Smith stripped away the volumetric qualities of sculpture and instead presented the figure as an aggressively two-dimensional presence in space. The first of the 1961 series, Two Circle Sentinel is the closest to human scale of those four. The open circle can be read as an eye, and the lower disc evokes the curve of a classic hip-shot pose. Additional elements welded to the main body of the figure capture light and shadow.