Your private grains are meant to stay private! You shouldn't be sharing them with the whole town, they're just for you.
This kanji also means I. Why? Because what's more private than you? I mean, I! Basically, some things are only the business of you (I) and those things should be private.
You're getting into the zone, thinking about yourself (I) and how much you love having things that are private and just yours, when you realize there is a sheep (し) in this grain bag. And it's eating all of your (I's) private grains. No!