The Zeroth Law of Thermodynamics says that if a change to the temperature(T) from one object (for example 'A') changes the temperature of another object ('B'), and a change to the temperature of 'B' changes the temperature of 'C' (a third object), then a change to the temperature of 'A' will mean a change to the temperature of 'C'. Heat naturally flows from areas that are hot to areas that are cold. 