Why is that?

Hello,

I'm currently studying for my chemistry exam. The topic is benzene and aromatic systems in general. I have two questions.

1.) If you look at the mesomeric properties of benzene, for example, you notice that the electrons in the ring are delocalized and therefore more stable than molecules with fixed bonds. Why is this so? What influence do delocalized electrons have on the stability of a molecule?

2.) There is a rule: The more mesomeric boundary structures a molecule can exhibit, the more stable it is. Why is this so?

I hope someone can find answers to my questions. Thanks!