expression
unavoidable; inevitable; cannot be helped
A formal, somewhat literary expression meaning that something is beyond one's control and must be accepted. Often used in historical or dramatic contexts.
戦となれば、是非に及ばず。
If it comes to war, it cannot be helped.
この結果は是非に及ばず、受け入れるしかない。
This outcome is unavoidable; we have no choice but to accept it.
Also means 'unavoidable,' but is slightly less formal than 是非に及ばず and more common in modern speech.
A classical Japanese expression combining 是非 (right and wrong; by extension, pros and cons) with に及ばず (cannot reach; cannot be helped). The exact historical derivation is uncertain, but it has been used since at least the Edo period.