Newton's rings are a wave phenomenon that posed a challenge for Newton, who favored the particle theory of light. In his work "Opticks," he introduced the concept of "fits of easy transmission and easy reflection" to explain the formation of these rings, aiming to create a unified model for optical phenomena. However, many of his ideas, including the fits, were not widely accepted or understood by his contemporaries. Newton viewed these fits as inherent properties of light rays rather than periodic influences, which distinguished his approach from that of contemporaries like Huygens. Ultimately, the explanation of Newton's rings reflects the complexities and limitations of early optical theories.