唐朝时期

姚洎世系不详，但是《旧唐书》、《新唐书》、《旧五代史》、《新五代史》都没有他的传记。他早年在荆南节度使（总部在江陵府，今湖北省荆州市）担任过幕府，和尚诗人贯休祝贺姚洎被从江陵召赴首都长安，担任拾遗，但不清楚这首诗是贯休何时所作。

天复二年（902年）唐昭宗被宦官韩全诲、张彦弘劫持，投靠凤翔节度使（治总部在凤翔府，今陕西省宝鸡市凤翔县）李茂贞。当时，姚洎和他的朋友韩偓都担任翰林学士，陪同皇帝在凤翔。李茂贞的对手宣武节度使（治总部在汴州，今河南省开封市）朱全忠率军围攻凤翔。五月二十五日，宰相韦贻范因母丧去职，宦官推荐翰林学士姚洎代为宰相。姚洎与韩偓商量，韩偓说：

姚洎于是称病，唐昭宗不允。结果在李茂贞及宦官的推荐下，六月初二，朝廷任命中书舍人苏检为工部侍郎、同平章事。七月，在李茂贞及宦官的压力下，昭宗召回韦贻范担任宰相，让韩偓草拟制书。韩偓拒绝，上疏称韦贻范居丧一月就要起复，有伤国体。八月二十六日，姚洎草拟制书命韦贻范复相。韦贻范不推辞，立即上表谢恩。然而不久，十一月，韦贻范病死。

当时，昭宗被软禁。十一月初二，昭宗派赵国夫人宠颜探查得知学士院二使都不在，便召翰林学士韩偓、姚洎，在土门外暗中相见，拉著手相对流泪。姚洎担心被别人看见，请昭宗快回去，昭宗于是离去。

天复三年（903年）李茂贞被迫投降，屠杀宦官，把皇帝献给朱全忠。韩偓和朱全忠和崔胤不和，被流放。之后一段时间，姚洎的事迹没有记录。

后梁时期

天佑四年（907年）朱全忠篡唐称帝，建立后梁，即梁太祖，姚洎以翰林学士擢兵部尚书知贡举。开平二年（908年）以兵部侍郎兼卤簿使。乾化三年（913年）朱全忠的儿子朱瑱即位，九月初五，以光禄大夫、守御史大夫姚洎为中书侍郎、同中书门下平章事，封吴兴郡开国侯。姚洎离任时间、去世时间不详。

During Tang Dynasty

Yao Ji's background is not clear, as there was no biography of his in the four relevant official histories — the Old Book of Tang, the New Book of Tang, the History of the Five Dynasties, and the New History of the Five Dynasties. However, it appeared that at some point he served as a staff member to the military governor of Jingnan Circuit (荆南, headquartered in modern Jingzhou, Hubei), as there is an extant poem by the Buddhist monk-poet Guanxiu to Yao congratulating him on being recalled from serving on staff at Jiangling Municipality (江陵), the capital of Jingnan Circuit, back to the capital Chang'an, apparently to serve as a low-level consultant in the imperial government, Shiyi (拾遗), but it is not clear when Guangxiu wrote it.

The first substantially datable historical reference to Yao was in 902, when then-reigning Emperor Zhaozong of Tang had been forcibly taken by powerful eunuchs, led by Han Quanhui and Zhang Yanhong (张彦弘), to Fengxiang Circuit (凤翔, headquartered in modern Baoji, Shaanxi), then governed by the eunuchs' ally Li Maozhen, the military governor (Jiedushi) of Fengxiang. At that time, both Yao and his friend Han Wo were serving as imperial scholars (翰林学士, Hanlin Xueshi) and had accompanied Emperor Zhaozong to Fengxiang; subsequently, Li Maozhen's rival Zhu Quanzhong the military governor of Xuanwu Circuit (宣武, headquartered in modern Kaifeng, Henan) put Fengxiang Circuit's capital Fengxiang Municipality under siege. When the chancellor Wei Yifan was forced to leave the imperial government for some time because his mother had died, the eunuchs initially recommended that Yao become chancellor to replace Wei. Han Wo recommended that Yao decline the commission:

Yao thus claimed to be ill and declined the commission, and Emperor Zhaozong himself was also not inclined to issue it. Instead, the position went to Su Jian. Later in the year, under the pressure from Li Maozhen and the eunuchs, Emperor Zhaozong was set to recall Wei back to the imperial government to again serve as chancellor, but when the draft edict was assigned to Han Wo to be written, Han refused to draft it — pointing out that having Wei return to the government after such a short mourning period was unseemly, so Emperor Zhaozong delayed the commission for some time. However, he eventually gave in to pressure, and had Yao instead draft it, and Wei was able to return as a chancellor. (Wei died shortly after, however.)

At that time, Emperor Zhaozong was under virtual house arrest. On an occasion late in 902, when the eunuchs guarding him were not around, he had his concubine, the Lady of Zhao, quickly summon Yao and Han Wo to his residence, for a brief meeting. He was, however, only able to hold their hands briefly and weep, before Yao reminded him that they might be discovered, and so they separated quickly.

In 903, Li Maozhen was forced to capitulate, slaughter the eunuchs, and surrender the emperor and the imperial household to Zhu. After that, while it is known that Han Wo was exiled for offending Zhu and Zhu's ally, the chancellor Cui Yin, historical references to Yao disappeared for some time.

During Later Liang

Zhu Quanzhong subsequently usurped the Tang throne, establishing a new Later Liang as its Emperor Taizu. In 913, by which time his son Zhu Zhen was emperor, Yao Ji, who was then serving as the chief imperial censor (御史大夫, Yushi Daifu), was given the chancellor designation Tong Zhongshu Menxia Pingzhangshi (同中书门下平章事), and was also made Zhongshu Shilang (中书侍郎), the deputy head of the legislative bureau of government (中书省, Zhongshu Sheng). He was also referred to at that time as the Marquess of Wuxing, presumably a title that was previously created him by a Later Liang emperor. That was the last historical reference to Yao, and it is not known when he left office or when he died.

Notes and references