All started with the invention of differential thermal analysis, DTA at the beginning of the 20th century. The tool was qualitative in the measurement of heat, but quantitative in measuring temperature. The differential scanning calorimetry, DSC, became popular in the 1970s. In certain temperature regions, it could replace even the more precise, but cumbersome, classical technique of adiabatic calorimetry. A large volume of quantitative thermodynamic information was accumulated. Both equilibrium and non-equilibrium data were collected. Unfortunately, the qualitative applications of the DSC grew even faster and overshadowed the quantitative capabilities of measurement of heat. The newer temperature-modulated DSC, TMDSC, makes use of the same instrumentation and seems to follow the same fate, despite the fact, that it can distinguish equilibrium from non-equilibrium, a key information needed in the thermodynamic description of materials. Seeing the growth of these efficient techniques, one could conclude that all questions one might have wanted to ask in 1900 can be answered now. A new question, however, has become important in the 21st century: What happens at the nanophase level and in the description of very fast processes? Are we able to learn from the past, or are we again to stay at the level of qualitative DTA?