King was arrested and jailed early in the campaign—his 13th arrest[104] out of 29.[105] From his cell, he composed the now-famous Letter from Birmingham Jail which responds to calls on the movement to pursue legal channels for social change. King argues that the crisis of racism is too urgent, and the current system too entrenched: "We know through painful experience that freedom is never voluntarily given by the oppressor; it must be demanded by the oppressed."[106] He points out that the Boston Tea Party, a celebrated act of rebellion in the American colonies, was illegal civil disobedience, and that, conversely, "everything Adolf Hitler did in Germany was 'legal'".[106] King also expresses his frustration with white moderates and clergymen too timid to oppose an unjust system: