Basically, the fox tricked the bird into dropping the meat. The crow felt the need to prove itself to the fox, therefore losing what it had already achieved. I hope that helps you understand!
A theme expressed in both "To My Dear Loving Husband" and "To the King's Most Excellent Majesty" is gratitude and loyalty.
This means that sometimes, you should trust your emotions rather than your brain. Sometimes, even if something seems logical in the first place, your heart may tell you that it is not right, or that it shouldn't be like that, and it may be the time to choose to follow your heart rather than your logic.
Well, Caliban is clever and quick-thinking