The point is not that this world is too sad to love or too glad not to love; the point is that when you do love a thing, its gladness is a reason for loving it, and its sadness a reason for loving it more.
It is very pleasant to scratch an itching ring-worm, but the sensation one gets afterwards is very painful and intolerable. In the same way the pleasures of this world are very attractive in the beginning, but their consequences are terrible to contemplate and hard to endure.
I remember, right after Hezbollah launched its rocket attacks on Israel, I said: This is a clarifying moment; this is a chance for the world to see the threats of the 21st century, the challenge we face.