|An example of a basic analogy (Ѻ) or comparison between two things in similarity, namely the front of a car and human face, according to which head lights are likened to eyes, the grill is likened to the mouth, the hood to the nose, etc.|
See main: Thermodynamic analogyIn 1952, English physicist C.G. Darwin defined 'human thermodynamics' as the "thermodynamic study of systems of human molecules", in his book in his The Next Million Years, wherein he used the word 'analogy' 19 times, comparing humans, by analogy, to the molecules of a body of gas governed by Boyle's law, to the behavior of a wild animal, and to the behavior of ants. The following are few representative quotes:
“The analogy I have cited of the gas laws is the simplest example that is furnished by statistical mechanics, and it is only fair to mention that, when the subject is pursued further, it does get a good deal more complicated. Thus much greater difficulties arise in considering how the gas can condense into a liquid or solid, but it would not be profitable to follow the analogy into these intricacies.
We may, so to speak, reasonably hope to find the Boyle's Law which controls the behavior of those very complicated molecules, the members of the human race, and from this we should be able to predict something of man's future.
The possibility depends on finding out whether there are for humanity any similar internal conditions, which would be analogous to the condition of being a conservative dynamical system, and external conditions analogous to the containing vessel.
In the gas, the external conditions were given by the containing vessel, and the analogy here is obviously the earth itself. The internal principle, which is to be analogous to the property of being conservative dynamical systems, of course lies deeper. It must depend on the laws governing the nature and behaviour of the human molecules. When I compare human beings to molecules, the reader may feel that this is a bad analogy, because unlike a molecule, a man has free will, which makes his actions unpredictable.
Though the individual collisions of the human molecules may be a little less predictable than those of gas molecules—which, as I have said, do not have to be considered in detail either—the census returns show that for a large population the results average out with great accuracy. The internal principle then of the human molecules is human nature itself. On the analogy between human history and the molecules of a gas, the different civilizations are to be ranked as fluctuations from the average.”
See main: Chemical analogy; Chemical aphorismIn 1800, German poet Friedrich Schlegel, supposedly, used a vast range of chemistry metaphors and allegory in his literary work; a subject on which he was said to have more than a passing knowledge of, but not a systematic understanding of. 
“I am aware that when I talk about human beings as combinations of chemicals it is like using an extremely crude, but nonetheless practical, graduated laboratory beaker as a measuring device. We can, I believe, employ the analogies and examples of chemical reaction and other reactions which each of us will develop out of experience with the confidence we feel when we take measurements with a yardstick.”
“People who love each other mix like water and wine; people who hate each other segregate like water and oil.”
“A catalyst is a substance that affects the rate of a reaction but emerges from the process unchanged. A man inciting a mob to riot and then ducking out before the tanks roll in can be regarded as a catalyst.”
“Animals are abstracted as local thermodynamic perturbations—repositories of chemical energy—whose feeding, metabolism, growth, and reproduction and analyzed by application of energy concepts of thermodynamics: calories, free energy, work, entropy, heat, efficiency, and productivity [modeled on] the basic assumption that flows of energy organize thermodynamic systems, including biological ones. Animals [are viewed] as repositories of multiple chemical elements; in the stoichiometric view, they are mixtures of multiple substances, as for example in the ‘human molecule’.”
“And I cherish more than anything else the ‘analogies’, my most trustworthy masters. They know all the secrets of nature, and they ought to be least neglected in geometry.”— Johannes Kepler (c.1620), Publication (Ѻ)