Salem had its "witches".

The 1940s and 1950s had its "reds" through the practice of McCarthyism.

The 1960s and 1970s had its concerns over USSR in Cuba.

The 1980s had the Cold War.

And now the 2000s have terrorism.

It looks like we've come full circle: starting off with imagination and sorcery; stumbling into a perceived threat which could have been real; then moving on to a very real threat; and now, once again, back to attempts to divine something from nothing and stoke people's imaginations for fear.