expression
not so; that is not the case
A classical or formal expression meaning 'it is not so' or 'that is not the case'. Often used to deny a preceding statement or assumption. In modern Japanese, it appears mainly in literary or rhetorical contexts.
彼の言うことはさにあらず、真実は別にある。
What he says is not so; the truth lies elsewhere.
世間の評判はさにあらず、彼は実直な人物だ。
Contrary to public opinion, he is an honest person.