にして ①At, Over, In, Only (after, when, or because)

These expressions are often found together because their meanings complement each other. にして suggests a significant occasion or example of something, while て初めて describes something happening for the first time 'only after' a certain event. Together, they can express an idea like 結婚10年目にして初めて二人で旅行した ('They vacationed together for the first time in their 10th year of marriage.').

These expressions are often found together because their meanings complement each other. にして suggests a significant occasion or example of something, while て初めて describes something happening for the first time 'only after' a certain event. Together, they can express an idea like 結婚10年目にして初めて二人で旅行した ('They vacationed together for the first time in their 10th year of marriage.').

These are the same combination of particle に and verb する and on a fundamental level have the same meaning of 'while being (A), (B)'. In practice, they may seem to have different functions, as にしては② expresses that something is two qualities at once, e.g. シンプルにして複雑 'both simple and complex', while にして① expresses something that is a condition for what follows, e.g. 30歳にして初めて海外旅行に行く 'to go on a trip abroad for the first time at thirty'.