There is no question that this is a philatelic cover -- 24c in postage for essentially cross-town delivery is a dead giveaway.
All of the stamps as well as the stamped envelope were issued in 1926 and they bear postmarks dated 23Oct1926, the last day of the second international philatelic exhibition to be held in the United States.

On the reverse is one of the exhibition labels, tied to the cover by an Ozone Park, NY receiving stamp.

Apart from the dates of his birth and death, I haven't been able to find anything definitive about the addressee but I'd bet a paycheck that he was a stamp collector!