Wisdom only comes from experience

Have you ever heard those sayings like: "never hit on a colleague" or "never work for a relative"?
I guess so, the truth is, we never learn it till we face the crude reality, till we stubbornly hit the ground named "personal experience" on that.
And so it happened to me: this summer I'm working for my uncle and, well: the saying is more than right about it,  it's sad but true.
As regards the other saying, I can guarantee it's true as well!
So Herman Hesse was right, I still haven't spot one big reason why, but the moral here is: "there's no wisdom without experience"!