Why every thing follows the law of concentration gradient

This law is obeyed by all things even energy flows from level of high conc to level of low conc.

Because given a lack of external forces, the all particles would like to follow the path of least resistance. Going to an area of high concentration takes more work than going to an area of low concentration. Unless something else is going on, a particle will always go where there is lower concentration.

I can't say why things work that way, but it's nice that they do. Many areas of physics are analogous to each other. Another example is the multitude of different inverse square laws. It's convenient because once you come up with the mathematical apparatus to solve one problem in physics, you'll often find that the solution can be applied to other areas too.

Well your question is about Newton's Second law of Thermodynamics. This happens to be the hardest one to understand. Here's the wikipedia article about it:

http://en.wikipedia.org/wiki/Second_law_…