The Chinese began to produce high-quality blue-and-white porcelains in the fourteenth century, soon after they gained access to cobalt oxide pigment from the Middle East. The cobalt is painted onto the white surface of the porcelain, then covered with glaze that becomes clear when fired, creating what is referred to as "underglaze blue" decoration. Ceramics made in this manner were most popular outside of China and became one of the region's major exports.
Brooklyn's wine jar is widely considered a masterpiece of blue-and-white porcelain for the deep color of its decoration, its strong contours, and the extraordinary fit of the design of fish and water plants to its form. Unlike the designs in other fourteenth-century ceramics, the jar's decoration of fish swimming among stylized plants fills the entire surface in one unified field, leaving only a small but powerfully drawn band of crashing waves around the neck. The names of the fish form a rebus—a wordplay on a four-character phrase meaning "honest and incorruptible." While the design might exhort the jar's owner to upright action, the wine it once contained remained a powerful reminder of life's temptations.