“No one shall persuade me that I am not a phase.” — Henry Adams (1908), age 70, after studying, for over a decade, the free energy work Willard Gibbs, applied socially

In hmolscience, a social phase is the concept of "phase", devised by Willard Gibbs (1876), employed to describe a person in a given physiochemical state (e.g. human phase) and or a society, social system, and or social entity in a given phase, phase point, or phase transition; synonymous, nearly, with the akin term "equilibrium".

Overview
In 1878, Friedrich Engels, in his Anti-Duhring, a work in opposition to the ideas of German philosopher Eugen Durhing (1833-1921), invoked water metaphors when he likened the revolutionary transformation of a society to the qualitative phase transformation of ice into water and water into steam. [5]

In 1890s to 1910s, Henry Adams was working on a Gibbs-based model of social phases; the following being a few representative quotes:

“On the physico-chemical law of development and dynamics, our society has reached what is called the critical point where it is near a new phase or equilibrium.”
— Henry Adams (1908), “Letter to Charles Gaskell”, Sep 27 [1]

“I have run my head hard up against a form of mathematics that grinds my brains out. I flounder like a sculpin in the mud. It is called the ‘law of phases’, and was invented at Yale [by Gibbs]. No one shall persuade me that I am not a phase.”
— Henry Adams (1908), “Letter to Elizabeth Cameron”, Sep 29 [2]

In 2005, Russian mathematical physicist Victor Sergeev, in his 155-page booklet The Thermodynamic Approach to Market, touches on phase transitions in social systems. [4]

Quotes
The following are related quotes:

“It is true that while we live, if we are cautious enough, we have the chance to prolong the time intervals between our human ‘phases’ so as to minimize encountering the phase points of life we call ‘accidents’.”
— Bruce Lindsay (1983). “Social Exemplifications of Physical Principles” [3]

See also
● Human phase

References
1. (a) Adams, Henry. (1908). “Letter to Charles Gaskell”, Sep 27.
(b) Adams, Henry. (1992). Henry Adams: Selected Letters (editor: Ernest Samuels) (pg. 504-06). Harvard University Press.
2. (a) Adams, Henry. (1908). “Letter to Elizabeth Cameron” (Sep 29), in: Letters of Henry Adams, 1892-1918 (editor: Worthington Ford) (pg. 510). Kraus Reprints, 1969.
(b) Schwehn, Mark R. (1978). The Making of Modern Consciousness in America: the Works and Careers of Henry Adams and William James (pg. 109). Stanford University.
3. Lindsay, Robert B. (1983). “Social Exemplifications of Physical Principles”; in: Old and New Questions in Physics, Cosmology, Philosophy, and Theoretical Biology: Essays in Honor of Wolfgang Yourgrau (editor: Alwyn Merwe) (§B7:647-58; quote, pg. 653). Plenum Press.
4. Sergeev, Victor (2005). The Thermodynamic Approach to Market (abs). Translated and edited by D. Leites. Leipzig: MPIMiS.
5. (a) Engels, Friedrich. (1878). Anti-Duhring. International, 1970.
(b) Rigney, Daniel. (2001). The Metaphorical Society: an Invitation to Social Theory (§3: Society as Machine, pgs. 41-62, esp. pg. 50). Rowman & Littlefield.
(c) Anti- Dühring – Wikipedia.