Richards' early work as a landscape painter was strongly influenced by the paintings of the Hudson River School, which was at that time in its most active and creative phase. These works followed the school's well-established formulas for depicting expanses of rural and wild scenery in a romanticized and stylized manner. In 1858, Richards saw an exhibition of English Pre-Raphaelite paintings in Philadelphia. These works displayed a hyperrealistic style, brilliant coloring, and often addressed subjects pertaining to history, literature, religion, or modern society.
Under the influence of the Pre-Raphaelites, Richard's landscape style changed dramatically, becoming more meticulous and precise. He abandoned the panoramic compositions he had favored earlier for more closely focused views of forest interiors with highly detailed foregrounds.October is of impressive scale for this period of his work, a marvel of careful observation and scrupulous portrayal reflecting the influence of the Pre-Raphaelite painters. The foreground, with its lovingly detailed rocks and plants, is overarched by trees resplendent with autumn foliage. In the distance, the forms of the forest dissolve in a radiant display of color and light, animated by small specks of blue sky revealed amidst the leaves.
The same year he painted October, Richards was elected a member of the Association for the Advancement of Truth in Art, a group of American Pre-Raphaelite followers who similarly sought spiritual truths through a diligent and detailed study of nature. Although this movement was relatively short-lived, lasting less than a decade, it resulted in a number of exceptional landscape and still life works by artists including Richards, Thomas Charles Farrer, and John Williams Hill. While Richards's Pre-Raphaelite paintings are considered by many to be his finest accomplishment, they are few in number. After 1867, the artist turned his attention to marine subjects, producing seascapes executed with an eye more focused on atmosphere and drama than exacting fidelity to nature.