(the reflexive form of one one 的反身形式 used as the object of a verb or preposition when ‘one’ is the subject of the verb or is understood as the subject （one 作动词的主语时，oneself 作动词或介词的宾语）自己，自身 used to emphasize one （用以强调 one）亲自，自己 One and oneself are very formal words and now sound old-fashioned. It is much more usual to use you and yourself for referring to people in general and I and myself when the speaker is referring to himself or herself.
Idioms
be oneself
(all) by oneself
alone; without anyone else （某人）独自，单独 Meditating by oneself is also beneficial. 自己冥想也是有益的。
without help （某人）独立地 Trying to manage all these changes by oneself is no good. 试图自己管理所有这些变化是没有好处的。
(all) to oneself
not shared with anyone 独享的；独自拥有的 Performance, even privately to oneself, is an art. 表演，哪怕是私下对自己，都是一门艺术。