Which is the best description of the first law of thermodynamics?

The first law of thermodynamics says that energy can neither be created nor destroyed; it can only be changed from one form to another. One of the implication of this is that the total energy of the universe is finite. Einstein's famous equation E=mc^2 provides a corollary to the first law by demonstrating that mass and energy are interrelated. Since they are related by his equation, the first law could be modified to say that the combination of mass and energy is finite for the universe,