86. Cause or reason may be expressed not only by an adverb (78) or a
clause (83), but also by use of the preposition "pro", because of, on
account of, for the sake of, for. It directs the thought away from the
complement toward the action, feeling or state caused by it, or done in
its interest or behalf:
La floroj velkas pro la seka vetero,
the flowers wilt because of the dry weather.
Mi skribis la leteron pro vi,
I wrote the letter for you (for your sake).
Pro tiuj nuboj mi timas ke pluvos,
on account of those clouds I fear that it will rain.
Oni sxatas cxerizojn pro la dolcxa gusto,
people like cherries because of the sweet taste.