I would like to tell you how much I respect you. You are bigger and greater than I can imagine. I wouldn't know how else to address you, except "Sir". I suppose it's an honorific that has fallen largely out of use, but it still holds the same amount of love, respect and honour in my heart.
I remember reading in those old story books where children would address their fathers as "Sir", and you are my Father. It is not a word to use lightly, and I hope I do not do so. I would not dishonour you, or your name.
They say your spirit abides with us, Sir, and I would like to thank you for this friend and helper that you have sent to us. I hope to be able to get to know him better, and that he would be able to give me fresh insights into your nature and character.
This will have to be a short letter, Sir.
Until next time,