einstein

* For clarity, I refer to the boy by both of his given names, Hans Albert, although his father invariably referred to him simply as Albert. At one
point, Einstein wrote a letter to his son and signed it “Albert” instead of “Papa.” In his next letter, he awkwardly began, “The explanation for
the curious signature on my last letter is that, in my absentmindedness, instead of signing my own name, I frequently sign for the person to
whom the letter is addressed” (Einstein to Hans Albert Einstein, March 11 and 16, 1916).