"We wrestle not against flesh and blood, but against principalities, against powers...against spiritual wickedness in high places." --Ephesians 6:12 This small but important book by Hendrik Berkhof ushered in a wave of studies on "the powers" spoken of in the New Testament, profoundly influencing William Stringfellow, Jacques Ellul, Marva Dawn, Walter Wink, and many others. John Howard Yoder brought it to an English-speaking audience for...