Letters from a Self-Made Merchant to his Son by George Lorimer

 A series of fictional letters from a wealthy pork-packer in the 1920s to his son. The first letter is when he's just been dropped off at Harvard to start his freshman year; he later joins his father's business; the last letter is when he tells his father he's getting married and his father "turns him over to his wife to keep him in order". It's written by the editor of the Saturday Evening Post and contains wonderful tidbits of advice about life and business, many of which are surprisingly current. 

Here's one from the first paragraph of the book: 

"What we're really sending you to Harvard for is to get a little of the education that's so good and plenty there. When it's passed around you don't want to be bashful, but reach right out and take a big helping every time, for I want you to get your share. You'll find that education's about the only thing lying around loose in this world, and that it's about the only thing a fellow can have as much as he's willing to haul away. Everything else is screwed down tight and the screw-driver lost."