Giovanni Benedetto Castiglione captured the dramatic consequence of Isaac's birth in the Old Testament. After Sarah, the aged wife of hundred-year-old Abraham, miraculously gave birth to Isaac, she forced her husband to cast out her servant Hagar and Ishmael, the son Hagar had already borne Abraham.
Castiglione's friezelike composition, with figures balanced carefully along the foreground plane in front of a classical architectural backdrop, reflects the influence of fellow Baroque artist Nicolas Poussin, whose circle Castiglione frequented in Rome.
Oil sketches emerged in the 1500s as a step in the preparation of a painting, but Castiglione was among the earliest artists to make them as independent, finished works of art. Castiglione "drew" with the brush in oils, using little color and thus conveying the effect of a drawing rather than a painting. He used white sparingly to highlight; most of the composition is sketched in thick, textural strokes of red-brown oil paint, enhancing the image's tone of dark, brooding emotion. Flatly painted areas of blue set off the figures from the background.