He thus left the capital scene and journeyed to Mount Lu to become a Taoist monk at Jianji Temple (簡寂宮).
He then changed back into the robes of a scholar, and went north to Later Liang's northern rival Jin, meeting Jin's prince Li Cunxu at Zhen Prefecture (鎮州, in modern Shijiazhuang, Hebei), although it was not stated whether Li gave him any positions in the government at that time.
[3] As of 927, by which time Li Cunxu had died and been succeeded by his adoptive brother Li Siyuan as emperor, Sun was serving as a secretary to Zhu Shouyin the military governor (Jiedushi) of Xuanwu Circuit (宣武, headquartered in modern Kaifeng, Henan).
[3][5] In winter 927, Li Siyuan suddenly announced that he was going to visit Xuanwu's capital Bian Prefecture (汴州) from the imperial capital Luoyang, leading to two rumors — either that he was intending to launch a major attack on Later Tang's southeastern neighbor Wu, or that he was going to act against one of the rebellious governors to the east.
However, Li Siyuan's generals Fan Yanguang and Shi Jingtang quickly arrived at Bian before its defenses could be fully ready and began the siege, and when Li Siyuan himself shortly arrived thereafter and continued the siege in earnest, the people of Bian began to desert Zhu in droves.
He sat on the bank of the Huai and acted crazy by grabbing his clothes and eating the fleas thereon, so the guards ignored him.
But the Master made you, Lord, a friend to the Prince of Qi in order to ask you to guide him with kindness and righteousness, not to spend time in entertainment and games with him.
[10] After Li Jing took the throne, at the urging of his younger brother Li Jingda (李景達), who apparently did not like Sun Sheng, Sun was sent away from the imperial administration to serve as the military governor of Yongtai Circuit (永泰, headquartered in modern Anqing, Anhui).
As a result of this incident, Sun was demoted to be the minister of palace supplies (光祿卿, Guanglu Qing).
However, Li Jing, who had respected Sun, did not further punish him, and later made him You Puye (右僕射, one of the heads of the executive bureau (尚書省, Shangshu Sheng)).
[3][11] In 952, Li Jing named Sun, along with Feng Yanji and Xu Jingyun (徐景運), chancellors with the designation Tong Zhongshu Menxia Pingzhangshi (同中書門下平章事).
When hearing of this, Sun, who had long disrespected Feng, made the comment, "Is it that gold goblets and jade bowls are going to contain dog feces?
"[12] At the time that Sun, Feng, and Xu became chancellors, Southern Tang had just destroyed its southwestern neighbor Chu, but was in effective control of only one of the three main circuits of Chu — Wu'an (武安, headquartered at Chu's formal capital Changsha, Hunan); the other two main circuits, Wuping (武平, headquartered in modern Changde, Hunan), and Jingjiang (靜江, headquartered in modern Guilin, Guangxi), remained out of Southern Tang's effective control, with Wuping effectively under the control of the warlord Liu Yan, and Jingjiang's having been seized by Southern Han when Chu fell to Southern Tang.
Li Jing initially did not want to carry out further campaigns over Chu territory, and therefore considered effectively letting Southern Han retain Jingjiang and bringing Wuping under only formal and not actual control by issuing a commission to Liu, allowing him to retain Wuping.
Sun agreed with this idea, but Feng opposed, believing that this would cause Southern Tang's conquest effectively meaningless.
Hearing of the defeat, Feng and Sun submitted petitions blaming themselves and asking to be relieved from their posts.
Li Jing initially declined, but upon Sun's insistence, removed them from their chancellorships and leaving them as Puyes.
Faced with this great crisis, Li Jing bestowed the grand title of Sikong (司空, one of the Three Excellencies) on Sun, and sent him with the minister Wang Chongzhi (王崇直) as emissaries to Later Zhou's emperor Guo Rong, offering to formally submit as a vassal and offering gifts, begging Guo to stop his attack.
[1] However, the terms that Li Deming and Zhong, and later Sun and Wang, offered Guo on their emperor's behalf, was not sufficient enticing to Guo, with his generals repeatedly prevailing over Southern Tang forces, causing him to want to take control of all of Southern Tang territory north of the Yangtze River, so he refused Li JIng's offer.
Guo agreed, and, at Sun's request, allowed Li Deming and Wang to return to Southern Tang's capital Jinling.