it is not so; it does not seem so
Archaic expression used in classical Japanese to deny a state or appearance. Not used in modern speech.
In classical texts, 然ならず is read as さならず and indicates that something is not the case.
it should not be so
Archaic expression conveying that something ought not to be the case. Found in older written language.
然ならず was used in old writing to mean 'it should not be so.'