Hatred of Jews is the most diagnosed and least treated of all social diseases. Why is this so? Antisemitism cannot be understood merely by examining the evil designs of ruthless tyrants or ignorant people. Rather it is often a useful tool of powerful social forces. It invariably also involves both its victims and its perpetrators in ways that are not always transparent. To suggest that Jews are in some way involved in the offenses perpetrated against them is not to blame the victim but rather to understand antisemitism as a dynamic force, one in which both Jews and those who discriminate against them are engaged in a macabre and often fatal dance. Jews are interstitial. Enmeshed in a larger social fabric, they have often become victims of tensions and conflict they neither understand nor control. By studying how individual Jews as well as entire Jewish communities have responded to the interstitial dilemma, the appeal of antisemitism can be better understood and confronted. Finally, the writings of Benedict Spinoza are seen as a relevant response to the interstitial analysis. This philosopher, who lived almost four hundred years ago, offers rich insights into the problems that confront not only the Jewish community but all of humanity.