[chryuop]

I didn't see any "only" implied in there. I thought that life can get luster and strenght if polished and tempered, but that doesn't exclude other things can give luster and strength as well.

I admit English is not my language and the phrase sounds pretty strange to my ears so I had problems in understanding if it was a matter of logical consequence (と) or more a matter of condition (and here we fall into those different ways of doing conditional that I never fail to get wrong in my exercises LOL).