Thembekile (known as Thembi) was Mandela's older son (with his first wife, Evelyn) and his third-born child. Because of his long working hours, Mandela did not spend much time with the boy and his siblings. He tells us how Thembi responded to that situation:
One day...my wife [Evelyn] informed me that my elder son, Thembi, then five, had asked her, "Where does Daddy live?" I had been returning home late at night, long after he had gone to sleep, and departing early in the morning before he woke. I did not relish being deprived of the company of my children. I missed them a great deal during those days, long before I had any inkling that I would spend decades apart from them. (Mandela, Long Walk to Freedom, page 119.)
After his parents divorced, Thembi was upset. Mandela tells us:
. . . Following the breakup, Thembi would frequently wear my clothes, even though they were far too large for him; they gave him some kind of attachment to his too-often-distant father. (Long Walk to Freedom, page 209.)
While Mandela was imprisoned on Robben Island, Thembi was killed in a car accident. His father was not allowed to attend the funeral of his twenty-five-year-old son.
Not long before Thembi died, Mandela had also lost his Mother. The anguished prisoner wrote the following words to a friend:
I have lost both Thembi and Ma, and I must confess that the order that had reigned in my soul has almost vanished.
Image online, courtesy Nelson Mandela.org.
Quoted passages, from Mandela's book Long Walk to Freedom.
Quote regarding Mandela's letter, from Nelson Mandela: A Life in Photographs (2009 Hardcover) by David Elliot Cohen and John D. Battersby.