it is so; it is as such
Archaic expression equivalent to modern そうである or その通りである. Found in classical Japanese texts.
In classical Japanese, 然有り was written and read as さあり, meaning 'it is so'.
Compound of classical adverb 然 (さ, 'so') and 有り (あり, 'to be'). The exact historical derivation is uncertain, but it follows a common classical pattern.