In human thermodynamics, thermodynamics of Goethe's Faust refers to the ideas presented at an 1892 lecture, titled "Goethe's Presentiments of Coming Scientific Ideas", held in the General Assembly of the Goethe Society in Weimar, in which German physician and physicist Hermann von Helmholtz attempted to explain German polymath Johann von Goethe's Faust through the lens of thermodynamics.  In this speech, Helmholtz postulates that Goethe was aware of the basics of the conservation of energy and argues that the ebb and flow of life, and its relation to death, has an explanation in the total constancy of energy or active force, for both animate and inanimate life. These ideas were precursors to the science of cessation thermodynamics, the study of death in relation to the first law of thermodynamics. 
The legend of Faust is a classic German Legend about a man named Faust that makes a pact with the Devil, a tale which goes back to at least the 16th century.  Goethe's version of Faust was highly-complex as compared to the original. The legend of Faust was an obsession of Goethe's. Although by no means a constant pursuit, the composition and refinement of his own version of the legend occupied him for over sixty years. The final version, not completely published until after his death, is recognized as a great work of German Literature.
In Goethe's version of Faust, the story concerns the fate of Faust in his quest for the true essence of life ("was die Welt im Innersten zusammenhält"). Frustrated with learning and the limits to his knowledge and power, he attracts the attention of the Devil (represented by Mephistopheles), with whom Faust makes a deal to serve him until the moment that Faust attains the zenith of human happiness, at which point Mephistopheles may take his soul. Goethe's Faust is pleased with the deal, as he believes the moment will never come.
In the first part, Mephistopheles leads Faust through experiences that culminate in a lustful and destructive relationship with an innocent and nubile woman named Gretchen. Gretchen and her family are destroyed by Mephistopheles' deceptions and Faust's desires and actions. The story ends in tragedy as Gretchen is saved and Faust is left in shame.
The second part begins with the Spirits of the Earth forgiving Faust (and the rest of mankind) and progresses into rich allegorical poetry. Faust and his devil pass through the world of politics and the world of the classical gods, and meet with Helen of Troy (the personification of beauty). Finally, having succeeded in taming the very forces of war and nature Faust experiences a single moment of happiness. Helmholtz explains this using thermodynamics. 
In particular, in an 1892 lecture titled "Goethe's Presentiments of Coming Scientific Ideas", Helmholtz cites the allegorical figure of the Earth Spirit which he says, in modern times, should be equated with organic life on Earth that, in thermodynamic terms, can be equated with “energy or effective motor power”, which constitutes the “active force … in the realm of the living nature and in inanimate bodies”.  Specifically, the passage to which Helmholtz refers in Faust, the Spirit says:
In the tides of Life,
in Actions storm,
A fluctuant wave,
A shuttle free,
Birth and the Grave,
An eternal sea,
A weaving, flowing
Thus at Time’s humming loom ‘tis my hand prepares
The garment of Life which Deity wears!