_Slavery._--At the beginning of the Christian era, slavery existed in every province of the Roman empire. Nearly everywhere the number of slaves was much greater than that of the free citizens. In Attica, according to the census of Demetrius Phalereus, about the beginning of the fourth century B.C., there were 400,000 slaves, 10,000 foreign settlers, and 20,000 free citizens. Zumpt estimates that there were two slaves to every freeman in Rome in the year 5 B.C. It frequently happened that a wealthy Roman possessed as many as 20,000 slaves. Slaves who gained their freedom might themselves become masters and own slaves. During the reign of Augustus, a freedman died, leaving 4,116 slaves. Crassus possessed so many that his company of architects and carpenters alone exceeded 500 in number. The principal slave markets of Greece were those at Athens, Ephesus, Cyprus, and Samos. In the market place of each of these cities, slaves were exposed for sale upon wooden scaffolds. From the neck of each was hung a tablet or placard containing a description of his or her meritorious qualities, such as parentage, educational advantages, health and freedom from physical defects. They were required to strip themselves at the request of purchasers. In this way, the qualifications of slaves for certain purposes could be accurately judged. The vigorous, large-limbed Cappadocians, for instance, like our modern draft horses, were selected for their strength and their ability to lift heavy loads and endure long-continued work.