In the English language as we use it now, words like progressive and conservative are actually relative designations. Progressive means "left of the mainstream" and conservative means "right of the mainstream." When the mainstream shifts, these words have to shift as well, and the result is that many of the radical left-wing ideas of 1907 would be radical right-wing ideas in 2007.

"Why there's no such thing as "liberal media bias"". - 2007