My wife recently bought me an old book. It's called The Mathematical Theory of Investment. It was written in 1913 and it's as dry and boring as it sounds (but the old weathered cover looks awesome on a bookshelf). I flipped through it and thought, "Does any of this matter?" These formulas, these charts, this data?Well, yes. But not nearly as much as the soft, behavioral side of investing. This episode shares 10 of what I think are the most critical financial skills -- none of which you'll find in a 100-year-old academic text.