Antisemitism can only be understood by tracing its deep historical roots, as well as its modern transformation. And because antisemitic arguments have always been answered by counterarguments, anti-antisemitism has a similarly extended and multifaceted history. Hence, over time, both have meant different things to different people, have been repeatedly mobilized for political ends, and have become dependent on one another. Long before the term antisemitism was coined, anti-Jewish animus played a role in how Jews were perceived by others, and how Jews interacted with the world and perceived themselves. Conversely, anti-antisemitic rhetoric gains public attention and visibility whenever it persuades the public that antisemitism is a real and present danger.