What is the name of the author that wrote a letter to his son about love,

[Jenny H]

when he heard his son met someone? I know the question is quite vague...but I remember reading a letter a long time ago that a man (I believe he was a well known author) wrote to his son when he heard his son had met a girl. The letter was about love. It was a beautiful letter and I want to read it again! This is driving me nuts!