This is not a homework problem. I want to relay a statement made by my professor. From his online script: "0th law of thermodynamics: If two subsystems I,II are separately in thermal contact with a third system, III, then they are in thermal equilibrium with each other." He stated this in class and I protested because I have always heard that system I and II must seperately be in thermal equilibrium with system III. He basically told me it didn't matter it means the same. I don't see how though, if I have three systems, eg bricks. One is in a freezer, one is in an oven and brick III is at room temperature. I take all bricks out and put I and II in contact (here I am considering thermal contact as physical contact) with brick III but not each other. Brick I and brick II are most certainly not in thermal equilibrium. Can you guys help me? What am I missing?