Both the general principle and the historical development of the Constant Rate Thermal Analysis (CRTA) and of the TG technique are described. It is shown that CRTA, whose aim is to reduce at will pressure and temperature gradients inside the sample, has a much more effective control on heat and mass transfer phenomena than conventional TG. The successes and failures of TG is shown. It is shown also how the field of CRTA is as broad as that of conventional TG since it uses the same technique and the same equipment but in a basically different way : CRTA is in some respects the opposite of TG.