A particle indicating means or role: 'by' or 'by means of' and also 'as' (in the role of); somewhat literary compared with で／として.
彼は医者にして詩人でもある。
He is a doctor and also a poet (as a doctor, he is also a poet).
連絡は電話にして行ってください。
Please contact me by telephone.
この作品は学者にしては難解すぎるが、一般には読みやすい。
This work is too difficult for a scholar (?), but generally readable.
Used in causative constructions as in '〜をして', indicating the agent or the person caused to act (literary/older style).
彼をして謝らせたのは私の失言だった。
It was my slip of the tongue that made him apologize.
師をしてその場を収めさせた。
He had the teacher restore order in that situation.
A connective use after the adverbial form of adjectives or the auxiliary ず, linking and indicating a state or condition (e.g., '安らかにして眠る').
安らかにして眠れ。
Rest peacefully.
静かにして話を聞きなさい。
Be quiet and listen.
An adverbial/particle use that can add emphasis or indicate a short time interval (e.g., '少しして' = 'a little while later').
少しして彼は戻ってきた。
A little while later he came back.
それにしても彼の才能は素晴らしい。
Even so, his talent is remarkable.
An archaic conjunction meaning 'and', 'so', or 'then' (literary); seldom used in modern colloquial Japanese.
行きてして還るもの多し（古文表現）。
Many things go and then return (classical expression).
言い終えてして、彼は席を立った。
Having finished speaking, he then stood up.