* * * * *
In 1914, it was enemy aliens.
In 1930, it was Wobblies.
In 1957, it was fellow-travelers.
In 1971, it was insane telepaths.
And, in 1973:
"We don't know _what_ it is," said Andrew J. Burris, Director of the
FBI. He threw his hands in the air and looked baffled and confused.