Who is Stanley Hart White from Letters of E. B. White and what is their importance?

Stanley is E.B. White's older brother, a hero in youth and a close friend throughout life. White writes copious and lengthy letters to his brother about everything in his life from career to marriage to children to aging and family concerns. Addressing his brother with the affectionate nickname of "Bun," White keeps close tabs on him although they live separate lives thousands of miles apart with Stanely in Chicago and E.B. In New York and Maine. Stanley seems to be the one member of White's nuclear family with whom he kept in closest touch throughout his life. When Stanley is stricken with a malignant tumor near his heart, his brother writes and offers to come to Chicago to "manage [his] doctors" at the Illinois Researchand Educatrional Hospital. The reader may feel a bit at a loss in understanding Stanley's side of the relationship since none of his correspondence is included in the book. However, it is evident that the relationship between the two White brothers was intimate and deeply-intertwined throughout their lives.