Why resonance makes the molecule stable?

Question

anonymous · Answer

A molecule or ion with  delocalized electrons is represented by several contributing structures  (also called resonance structures).Electron delocalization lowers the potential energy of the substance and thus makes it more stable than any of the contributing structures. This is why resonance makes a molecule more stable.

anonymous · Answer

But why electrons deloclization reduces the potential of the molecule?

anonymous · Answer

The Delocalization of the π-electrons lowers the orbital energies, imparting this stability.

anonymous · Answer

still I need to know why such delocalization reduces the energy ?