General Equilibrium Theory
  
Recently promoted from Colonel Equilibrium Theory...congrats.
You're sitting on the beach watching the waves roll in. All the water is trying to level out, but it never truly reaches the point of being level.
Now image all the bodies of water in the world trying to level out at the same time. An all-around perfect calm of all water, nothing flowing rapidly or changing.
Supply and demand in all markets are like those waters, trying to level out and equal each other, but not reaching the desired level. Some markets may find that point of equality, but not all of them at once.