1. the four elements: earth, water, fire, and wind (Buddhism)
2. the four freedoms: speaking out freely, airing views fully, holding great debates, and writing big-character posters, 大鳴大放|大鸣大放[da4 ming2 da4 fang4], 大辯論|大辩论[da4 bian4 lun4], 大字報|大字报[da4 zi4 bao4] (PRC)