In chemistry, affinity chemistry was subject of study, dominant between 1718 and into the 1830s, that sought to explain chemical reaction via various theories of chemical attraction or “affinity”, such as chemical affinity or elective affinity, preexisting, in various levels, between all chemical species or elements. [1]

History
The name affinitas was first used in the sense of chemical relation by Albertus magnus in circa 1250. What is called the "old theory" of elective affinity tends to refer to the works of English chemist John Mayow (1674), French chemist Étienne Geoffroy (1718), and Swedish chemist Torbern Bergmann (1775). [2] It was Geoffroy, however, who made the first affinity table (logic culled from Query 31 of Isaac Newton's Opticks; thus establishing affinity chemistry as a branch of science and invariably giving seed and momentum to the chemical revolution. [3]

Incorporation into modern theory
In 1852, though the “theory of chemical valencies” of English chemist Edward Frankland, the degree of affinity attachment of each species was beginning to be incorporated into the soon-to-be science of quantum chemistry (1910s), solidifying eventually with American chemical engineer Linus Pauling’s 1928 article “On the Nature of the Chemical Bond”; and in the 1870s, the measure of affinity was determined to be that of free energy, thus incorporating this aspect of affinity chemistry into the new science of chemical thermodynamics, and beginning [4]

Affinity chemistry is still to be found in modern science, albeit it is buried deep inside of connective theories of logic, such as affinity chromatography. [5] Likewise, in the modern drug-receptor thermodynamic theory of “drug-receptor affinity”, affinity is defined as the “tendency of a drug molecule to bind to a receptor”, a movement process quantified by intricate Gibbs free energy models. [6]

Human chemistry
German polymath Johann Goethe based his 1809 romance novella Elective Affinities on the work of Bergmann, arguing a theory that human relationships, specifically in reference to the passions of love, are determined by elective affinity preferences. [7] This publication thus founded the science of human chemistry; albeit the modern version uses the logic of chemical thermodynamics and quantum chemistry to argue the same view. [8]

References
1. (a) Comstock, John Lee. (1825). A Grammar of Chemistry (section 49: Affinity, pgs. 41-55). S.G. Goodrich.
(b) Turner, Edward and Bache, Franklin. (1830). Elements of Chemistry (Section I: Affinity, pgs. 102-114). John Grigg (publisher).
2. (a) Partington, J.R. (1937). A Short History of Chemistry (pgs. 137, 322). Dover.
(b) Geoffroy, Étienne F. (1718). Tableau des différentes Rapports Observées entre Différentes Substances (Table of the Different Relations Observed between Different Substances). France.
(c) Bergman, Torbern. (1775). A Dissertation on Elective Attractions. London: Frank Cass & Co.
3. Kim, Mi Gyung. (2003). Affinity, That Elusive Dream – A Genealogy of the Chemical Revolution. Cambridge, Mass: The MIT Press.
4. Levere, T. (1993). Affinity and Matter – Elements of Chemical Philosophy [1800-1865]. New York: Taylor & Francis.
5. Mohr, Peter and Pommerening. (1985). Affinity Chromatography (section: History of Affinity Chromatography, pgs. 7-18). CRC Press.
6. Raffa, Robert B. (2001). Drug-Receptor Thermodynamics - Introduction and Applications (Section: Drug-Receptor Affinity, pg. 4). New York: John Wiley & Sons.
7. Goethe, Johann. (1809). Elective Affinities. New York: Penguin Classics.
8. Thims, Libb. (2007). Human Chemistry (Volume Two), (preview), (ch. 10: "Goethe's Affinities", pgs. 371-422). Morrisville, NC: LuLu.