He (Dietrich Bonhoeffer) smoked many cigarettes when he engaged in difficult negotiations or concentrated writing. In conversation, he was an attentive listener, asking questions in a manner that gave his partner confidence and led him to say more than he thought he could. Bonhoeffer was incapable of treating anyone in a cursory fashion. He preferred small gatherings to large parties because he devoted himself entirely to the person he was with. 

~ Eberhard Bethge, Dietrich Bonhoeffer: A Biography (Revised Edition); Portrait (1970), xvii-xviii.

Dietrich Bonhoeffer, 1939