With a comparative or with more and a verb phrase, establishes a correlation with one or more other such comparatives.
It looks weaker and weaker, the more I think about it.
With a comparative, and often with for it, indicates a result more like said comparative. This can be negated with none. See none the.
I'm much the wiser for having had a difficult time like that.
For each; per.
valued at half a pound the bushel; paying seven dollars the year interest