COURSE OF PRIESTS AND LEVITES. Because of the great increase in the number of priests, David divided them into twenty-four relays (1 Chron 24:1-19). The priests were expected to serve from twenty years of age (1 Chron 23:6, 27). Sixteen courses were allotted the descendants of Eleazar and eight to those of Ithamar, his brother. Apart from the main festivals, when all the courses were active, each course ministered for a week, changes being made on the Sabbath before the evening sacrifice (2 Kings 11:5, 9). Courses were determined by casting lots.