How can one say that existence is good, without using Divine Revelation?

It's well known that one can prove the existence of God through the light of natural reason alone (e.g. the Five Ways). However, Divine Revelation would also show this. It is in Divine Revelation that we learn that creation/existence is *good* (Genesis 1:31). Could we also reach that same conclusion (with the same meaning of "good") with the light of natural reason?