The Chicago jail sentences were followed by six months at Woodstock and it was here that Socialism gradually laid hold of me in its own irresistible fashion. Books and pamphlets and letters from socialists came by every mail and I began to read and think and dissect the anatomy of the system in which workingmen, however organized, could be shattered and battered and splintered at a single stroke. The writings of Bellamy and Blanchford early appealed to me. The “Cooperative Commonwealth’ of Gronlund also impressed me, but the writings of Kautsky were so clear and conclusive that I readily grasped, not merely his argument, but also caught the spirit of his socialist utterance—and I thank him and all who helped me out of darkness into light.
It sounds to me that even though, yes, he was arrested, which isn't fun, I believe he is grateful for the time he was there because he truly understood and found his identity as a socialist, and not only that, but he also received letters of support from other socialists.