Before addressing the angry crowd, the politician paused to collect himself.

collect 在这里是动词，本意是"收集、聚集"，引申为"集中、整理"的意思。 himself 是反身代词，指代主语"the politician"自己。 collect oneself 是一个固定短语，意思是"让自己镇定下来、集中精神"，指通过短暂的停顿来调整情绪或思绪。