Is Everything Relative ?

I had a big ‘existential’ problem lately. It was about how the notion of Relativity is generalized by some friends of mine to nearly everything in our society and even to the truth itself. It was a big and long dispute. I found it strange that I had a different idea about the subject.

It was practically the refrain of modern life I doubted: "Everything's relative."

• Please ask yourself very carefully, if this statement is really true
  
• Did Einstein showed exactly that, in his work ?
• Can Einstein's Relativity Theory be considered also a Philosophical Theory not only a physical one ?

After some moments of thought, you can find the answer here, competently exposed by the Emeritus Professor of Philosophy, Ray Bradley.