In response to JeepersCripes9's comment:
Ha! Have you been to a real orthodox jewish wedding?
Knowledge, as in things you have leared along the way in your life that you could teach your children/next generation. To find cures for diseases, to invent, to create things that better our society. I think you always want the next generation to be better than the last.
I agree with the wealth part but I don't think that its required for a marriage that you share knowledge. Also, I don't believe that a marriage has to be for the betterment of society but you've already said that.
You could imagine a married couple where one of them is in the CIA. This person would have a lot of knowledge that they wouldn't be able to share. But the couple would still be married right?