AtD translation: This was spirit, after all.

[Mike Jing]

P172.26-32   Did something, something essential, happen to human
personality above a certain removal from sea level? Many quoted Dr.
Lombroso’s observation about how lowland folks tended to be placid and
law-abiding while mountain country bred revolutionaries and outlaws. That
was over in Italy, of course. Theorizers about the recently discovered
subconscious mind, reluctant to leave out any variable that might seem
helpful, couldn’t avoid the altitude, and the barometric pressure that went
with it. This was spirit, after all.

What is being implied by the last sentence?

P.S.
I've been working on a translation of Solaris for about a month. There's
another book coming up as well, but I'll try to squeeze in some work on AtD
whenever I can.