The Zeroth Law and the First Law

Thermally equilibrium states that if objects of different temperatures are brought into contact heat is transferred from the hotter object to the cooler object. This continues until the temperature which remember is the average kinetic energy of the particles in those objects of the two objects is equal at which point the objects are said to be in thermal equilibrium. So onto the zeroth law. If an if object A is in thermal equilibrium with object B and object B is in thermal equilibria with object C then objects A and C are also in thermal Equilibrium with each other. Now that doesn't sound particularly interesting it's just saying basically if A equals B and B equals C then A equals C. The reason that