"Those field workers are Cherumans—a caste so low that they can pollute a Nayar from a distance of sixty-four feet," Jack explained, "whereupon the Nayar is obligated to kill them, and then purify himself with endless and pompous rites. So to save themselves from being killed, and the Nayars from being inconvenienced, they cry out Popo! all the time, to warn all comers that they are present."