His move from Imperialist to Pacifist apparently took place in a 5 minute mystical span, an event which took place in 1901 during a visit to his friend's house, Prof. Whitehead. He writes:
Suddenly the ground seemed to give way beneath me, and I found myself in quite another region. Within five minutes I went throughHere, then, is one atheist reason for being a pacifist. All that is good, his view holds, comes from love, and war is its opposite. He had this epiphany watching the wife of Whitehead undergo severe agony, and his human response was to dedicate his life to the irradication of suffering. "The echoes of pain reverberate in my heart.... pain makes a mockery of what human life should be." This pain is caused by, not ended, by war, says the pacifist.
some such reflections as the following: the loneliness of the human soul is unendurable; nothing can penetrate it except the highest intensity of the sort of love that religious teachers have preached;
whatever does not spring from this motive is harmful, or at best useless; it follows that war is wrong, that a public school education is abominable, that the use of force is to be deprecated, and that in human relations one should penetrate to the core of loneliness in each person and speak to that.