The randomness, probability, organization, and information that are attributed to a greater or lesser entropy of substances are all perceptual manifestations of the same basic phenomenon, which is the absorption of thermal energy. Entropy is a mathematical function not having a physical reality characteristic of material bodies, but when multiplied by the temperature for which the entropy has been calculated the product becomes the quantity of thermal energy that must be absorbed for a substance to exist at that temperature above absolute zero. For the standard temperature, (TS0)-S-0 = Q(0). The advantage of visualizing entropy in this respect is discussed, and the suggestion made that the equation Delta G(0) = Delta H-0 - Delta Q(0) is a useful and, perhaps, more understandable form of the Gibbs free-energy equation. The distinction is made between changes in absorbed (entropic) thermal energy (Delta Q(0)) and exergonic thermal energy (Delta G(th)(0)), resulting from the conversion of non-thermal free energy into heat), the sum of which is the enthalpy change (Delta H-0) of the closed systems being considered, i.e. Delta H-0 = Delta G(th)(0) + Delta Q(0).