When we came home, we found Mrs Whitehead undergoing an unusually severe bout of pain. She seemed cut off from everyone and everything by walls of agony, and the sense of the solitude of each human soul suddenly overwhelmed me. Ever since my marriage, my emotional life had been calm and superficial. I had forgotten all the deeper issues, and had been content with flippant cleverness. Suddenly the ground seemed to give way beneath me, and I found myself in quite another region.
Source: The Autobiography of Bertrand Russell, v.1 chap. 1
More info.: https://russell-j.com/beginner/AB16-030.HTM