The remarkable Little Johnny Sylvester collection is coming to market with Grey Flannel Auctions in 2014, highlighted by a famous Babe Ruth signed baseball.
Eleven-year-old Yankees fan Sylvester was gravely ill in hospital following a horse riding accident, when Ruth sent him a signed baseball as a "get well" gift in October 1926.
On that baseball Ruth had inscribed "I'll Knock A Homer For You", a reference to the Yankees' World Series contest with the St Louis Cardinals.
Ruth was better than his word, smashing three home runs (a new personal best) in game four of the series.
Ruth sent two subsequent letters to the boy, whose spirits were much raised by the correspondence, and even the Yankees' seven-game loss couldn't prevent him from making a full recovery.
The baseball and letters are up for grabs at the February 6-ending online auction, in the 100th year since Ruth made his major league debut with the Boston Red Sox.
They are joined by a letter to Sylvester from American football star "Red" Grange - a friend of Ruth's - as well as a signed tennis racquet to the boy from "Big Bill" Tilden.
All the items, consigned directly from John Sylvester Jr, have been on loan to the Babe Ruth Museum since the 1980s.
Ruth's centenary year is shaping up to be an exciting one for baseball collectors. Goldin Auctions will sell a number of Ruth game-used bats, as well as an example of his 1914 rookie card, on July 12.
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The Babe Ruth memorabilia market scarcely needs an important anniversary to give it added impetus: his earliest game-used jersey made $4.4m in 2012 - a sports memorabilia record.