animal spirits

From Middle English spirite animal; equivalent to animal (adjective) +‎ spirits.^[1]

animal spirits pl (plural only)

1. (medicine, now historical) The theorized ‘spirits’ or physiological principles which allowed for sensation and voluntary movement. [from 15th c.]
   • 1621, Democritus Junior [pseudonym; Robert Burton], “Of the force of Imagination”, in The Anatomy of Melancholy, […], Oxford, Oxfordshire: […] John Lichfield and Iames Short, for Henry Cripps, →OCLC, partition 1, section 2, member 3, subsection 2, page 123:

     This is likewiſe evident in ſuch as walke in the night in their ſleep, and doe ſtrange feats: theſe vapours moue the Phantaſie, the Phantaſie the Appetite, which mouing the animall ſpirits, cauſeth the body to walke vp and downe, as if they were awake.

   • 1723, Charles Walker, Memoirs of Sally Salisbury, section VI:

     His Brains will be found situated at the Head of the Os Pubis: His Animal Spirits acting more vigorously in that Part, than in the Upper Region.

   • 1759, Lawrence Sterne, The Life and Opinions of Tristram Shandy, Gentleman, Folio Society, published 2005, page 19:

     you have all, I dare say, heard of the animal spirits, as how they are transfused from father to son &c. &c.—and a great deal to that purpose:– Well, you may take my word, that nine parts in ten of a man's sense of his nonsense, his successes and miscarriages in this world depend upon their motions and activity [...].

2. Liveliness, vivacity, a happy tendency to action. [from 18th c.]
   • 1813, Jane Austen, Pride and Prejudice, Plain Label, published 1975, page 63:

     She had high animal spirits, and a sort of natural self-consequence, which the attention of the officers, to whom her uncle's good dinners, and her own easy manners recommended her, had increased into assurance.

   • 1936, John Maynard Keynes, The General Theory of Employment, Interest, and Money, page 161:

     Most, probably, of our decisions to do something positive, the full consequences of which will be drawn out over many days to come, can only be taken as a result of animal spirits — of a spontaneous urge to action rather than inaction, and not as the outcome of a weighted average of quantitative benefits multiplied by quantitative probabilities.

3. (economics) After Keynes (citation 1936, above), the emotional and intuitive factors that drive business decisions whether to make investment gambles. [from 20th c.]
   • 1975, Hyman P. Minsky, John Maynard Keynes, page 11:

     This flaw exists because the financial system necessary for capitalist vitality and vigor — which translates entrepreneurial animal spirits into effective demand for investment — contains the potential for runaway expansion, powered by an investment boom.

   • 2005, Roger S. Frantz, Two minds: intuition and analysis in the history of economic thought, page 91:

     The existence of animal spirits does not imply that "irrational psychology" is the controlling factor in business and economics.

   • 2006, Robert J. Shiller, Irrational Exuberance, page 233:

     One of John Maynard Keynes's most famous terms, "animal spirits," is another name for much the same concept as irrational exuberance

• spirit animals