The six offices of
周礼 were named Heaven, Earth, Spring, Summer, Autumn and Winter, headed by the
冢宰,
司徒,
宗伯,
司马,
司寇 and
司空. Later dynasties matched them to the six ministries, so the Ministry of Personnel,
吏部, inherited the name. The section of the book on this office is cited as 《
周礼·
天官》.