Edited by David H. Lowenherz

Some of Mozart's sweetest notes had nothing to do with music. Away from home in 1789, he wrote to his wife, Constanze, about a portrait of her: "When I take it out of its case, I say...'Good-day, little rascal'...and when I put it away again...'Good night, little mouse, sleep well.'"

Love turns everyone to mush in this collection of historic letters. Ronald Reagan wrote about himself and Nancy in the third person: "Nancy Davis, seeing the plight of a lonely man...determined to rescue him," reads one 1981 note. Elvis Presley fan Marjorie Fossa said it with capitals after seeing the King perform in 1972: "I AM NOW ON CLOUD 9,000." Lowenherz's choices—from Henry VIII to George Custer—are passionate and poignant, and there isn't an e-mail among them. (Crown, $20)

Bottom Line: A Valentine's Day gift for your little mouse