In ancient Roman religion, the Cerealia was the major festival celebrated for the grain goddess Ceres. It was held for seven days from mid- to late April. Various agricultural festivals were held in the "last half of April". The Cerealia celebrated the harvest, and may have begun on the 19th. Surviving descriptions of Rome's city festival of Ceres are presumably urban versions of an originally rustic, agricultural festival. In his treatise on agriculture, Cato the Elder recommends that farmers sacrifice a sow to Ceres, before the harvest.