In human behaviors, struggle is a term that typically refers an uphill climb, movement through a path of resistance, or activity in adversity. [1] In 1798, English economist Thomas Malthus argued that life is a struggle for existence; this logic was taken up by English naturalist Charles Darwin in his famous 1859 Origin of Species (chapter three: “Struggle for Existence”); and in 1886 Austrian physicist Ludwig Boltzmann, a fan of Darwin’s theory, famously propositioned that life is a struggle for entropy. This proposition soon came under attack and more theoretical or rather thermodynamic struggles soon began to be proposed. Some of these various “struggles” and are tabulated below:

#	Date	Theory	Person
1.	1798	“Life, being that food and room are in limited supply, is a struggle for existence.”	Thomas Malthus [2]
2.	1886	“The general struggle for existence of animate beings is not a struggle for raw materials – these, for organisms, are air, water and soil, all abundantly available – nor for energy, which exists in plenty in any body in the form of heat Q, but of a struggle for entropy S, which becomes available through the transition of energy from the hot sun to the cold earth.”	Ludwig Boltzmann [3]
3.	1905	“[The] struggle for existence is a struggle for free energy available for doing work.”	Ludwig Boltzmann [8]
4.	1955	“The whole of life and civilization as we know it depends on thermodynamic instability; the struggle for existence is a struggle for free energy available for doing work.”	Anon [7]
5.	1959	“All life is a struggle for free energy.”	Leslie White [4]
6.	1963	“Man's whole struggle … practically every element in man’s developed civilization, may be interpreted either as an instinctive or conscious and deliberate attempt to replace disorder with order, in other words to consume entropy.”	Robert Lindsay [5]
7.	1967	“Power may be defined, for every society, as resulting from the need to struggle against the entropy that threatens it with disorder.”	Georges Balandier [9]
8.	1993	“Conflict (and ultimately war) does not arise between human and nature; rather, the struggle is between more developed systems and something else that is necessarily less developed and that the physicists know as entropy.”	Jean-François Lyotard [6]

References
1. Struggle quotes – ThinkExist.com.
2. Malthus, Thomas. (1798). On Population, (quote: "the perpetual struggle for room and food", chapter iii. p. 48). Augustus M Kelley Publishers.
3. Boltzmann, Ludwig. (1886). The Second Law of Thermodynamics. In B. McGinness, ed., Ludwig Boltzmann: Theoretical physics and philosophical problems: Select Writings. Dordrecht, Netherlands: D. Reidel, 1974.
4. White, Leslie. (1959). The Evolution of Culture: the Development of Civilization to the Fall of Rome (pgs. 40, 49). McGraw-Hill.
5. Lindsay, Robert B. (1963). The Role of Science in Civilization (pg. 291). Westport: Greenwood Press. Dowden, Hutchinson & Ross.
6. Lyotard, Jean-François. (1993). Political Views (pg. 99-100). University of Minnesota Press.
7. (a) Anon. (1955). Encyclopedia Britannica, Vol. 22, pg. 86.
(b) Blackburn, Richard J. (1990). The Vampire of Reason: an Essay in the Philosophy of History (pg. 21). Verso.
8. (a) Boltzmann, L. (1905). Populare Schriften. Leipzig: J. A. Barth.
(b) Brown, James G. (). Macroecology (pgs. 184, 238).
9. (a) Balandier, Georges. (1967). Anthropologie politique. Paris.
(b) Balandier, Georges. (1970). Political Anthropology. Allen Lane.