第二阶段(一九五一至一九五七年):我引导他进入统计力学与对称原理的研究。在这段时问内我们亲如兄弟,合作无间。我知道他不愿被别人认为是我的副手,所以「Keenly aware that he had to get out of my shadow. I bent over backward to attempt to help him in his career while maintaining strict public silence about the nature of the partnership.」 (我的选集,第54页。)