A second-generation painter in the Hudson River style, Casilear made numerous sketching trips with artist friends, such as Durand, Kensett, and Benjamin Champney, in the Catskills, the Adirondacks, the White Mountains, and the Genesee Valley. Like his contemporary, Sanford Gifford, Casilear strove to depict the light and atmosphere associated with a specific locale and time of day. In this regard, he is sometimes associated with the Luminist painters, though his work lacked the hard-edged static quality of mainstream Luminists like Heade and Lane. The nineteenth-century art critic, Henry Tuckerman, stated of Casilear’s paintings, “They are finished with great care, and the subjects chosen with fastidious taste; the habit of dealing strictly with form, gives a curious correctness to the details of his work; there is nothing dashing, daring, or off-hand; all is correct, delicate, and indicative of a sincere feeling for truth, both executive and moral; not so much a passion for beauty as a love of elegance is manifest…” (quoted in American Paradise:The World of the Hudson River School, the Metropolitan Museum of Art, p. 144)
Casilear’s work can be found in the Metropolitan Museum of Art, the Museum of Fine Arts, Boston, the National Gallery of Art, the Brooklyn Museum of Art, the Wadsworth Atheneum, the White House, the National Academy of Design, the Butler Institute of American Art, the Detroit Institute of Arts, and many others.