Signac was a leading practitioner of the Neo-Impressionist style originated by Georges Seurat, which abandoned the free brushwork of Impressionism in favor of a systematic application of tiny, distinct touches of pure color. Port of Saint-Cast is one of a series of four seascapes that Signac painted along the Brittany coast. The composition is spare and carefully balanced, with the stillness created by Signac's painstaking method enlivened by vibrant color and light. The idea of working in series may have come from Claude Monet, who had begun his paintings of the Creuse Valley several years earlier.