Is the clause "it's past doubt" archaic?

Question

From another version of this book I know the clause in boldface can be reworded as "It's certain". I searched the phase "past doubt" in Google but few related results were returned. So I wonder if this usage is a very old-fashioned.

In a word, however useful medicine well administered may be to us who live in a state of society, it is still past doubt, that if, on the one hand, the sick savage destitute of help, has nothing to hope from nature, on the other, he has nothing to fear but from his disease; a circumstance, which often renders his situation preferable to ours.

-- from Rousseau's “Discourse on Inequality”

Answer 1

The original sentence (p.23):

Enfin, quelque utile que puisse être parmi nous la médecine bien administrée, il est toujours certain que si le sauvage malade abandonné à lui-même n'a rien à espérer que de la nature, en revanche il n'a rien à craindre que de son mal, ce qui rend souvent sa situation préférable à la nôtre.

In this case, "il est toujours certain" is translated "it is still past doubt". Judging by COHA and Google's Ngram Viewer the version with past was never popular, but what results I can find for it were mostly in the early 1800s. I suppose you could call it archaic.

In any case, "past doubt" could be replaced with the more common "beyond doubt", which is a relatively common phrase meaning "certain to be true". Dictionary.com lists beyond doubt as an idiom meaning "with certainty; definitely".