I always liked Lynn White's story about how the stirrup revolutionized warfare and made feudal society and culture possible. Or Lefebre des Noettes' argument about how the invention of the rudder made extensive sailing and the consequent expansion of Europe and its colonization of the world possible. But it's sobering to realize that it took us over one thousand years to realize the impact of these artifacts. So I am not at all sure we have at this time a good grip on what the most important inventions of the past millennia have been. Certainly the contraceptive pill is a good candidate, and so is the scientific method. I am also intrigued by the effects of such inventions as the flag — a symbol of belonging that millions will follow to ruin or victory independently of biological connectedness; or the social security cardthat signifies that we are not alone and our welfare is a joint problem for the community; or the invention ofcivil rights which however abused and misused is pointing us towards a notion of universal human dignity that might yet eclipse in importance all the technological marvels of the millennium.