In the long run we are all Baroque

Terence Hutchison concluded his appendix on "Some postulates of economic liberalism" in Significance and Basic Postulates of Economic Theory with the admonition, "It is high time to put these theories [laissez faire and equilibrium doctrines] firmly back in their place as Utopian constructions." He cited S. Bauer's 1931 article, "Origine utopique et métaphorique de la théorie du “laissez faire” et de l’équilibre naturel."

Prominent in Bauer's discussion is the role of Baltasar Gracian's Oráculo Manual, which was translated into French by Amelot de la Houssaie in 1684, in popularizing both the notion and the term, laissez faire. Pierre le Pesant Boisguilbert is credited with introducing the term into political economic thought in a book published in 1707. It is conceivable that Keynes knew of the Gracian maxim because he used the image Gracian had used of tempestuous seas in his famous rejoinder about "the long run" being "a misleading guide to current affairs."

In his book Hutchison noted that "several writers have argued that some such postulate as 'perfect expectations' is necessary for equilibrium theory." This observation lends a special note of irony to Gracian's coinage of laissez faire. In his discussion of Gracian's Oráculo, Jeremy Robbins highlighted the observation that:

Gracián’s prudence rests firmly on a belief that human nature is constant... In Gracián’s case, human nature is viewed as a constant in so far as he believes it to act consistently contrary to reason."

In fact, Robbin's chapter on Gracian is titled "The Exploitation of Ignorance." Gracian's maxims establish "a sharp distinction between the elite and the necios [that is, fools]." Assuming that most people are fools who act contrary to reason is obviously something quite different from assuming perfect expectations. For that matter, the prudence of a courtier seeking to gain power over others is something quite distinct the foresight required of a policy professional acting ostensively on behalf of the public welfare.

That metaphorical and Utopian notions of laissez faire and natural equilibrium have managed to persist and even prevail in economics -- impervious to Hutchison's warning (or Keynes's) -- is testimony to the perceptiveness of Gracian's estimate of human nature.
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John Maynard Keynes, A Tract on Monetary Reform (1923)

Economists set themselves too easy, too useless a task if in tempestuous seasons they can only tell us that when the storm is long past the ocean is flat again.

Baltasar Gracian, Oráculo Manual y Arte de Prudencia, Maxim 138 (1647), English translation: The Art of Prudence.

The Art to let things go as they can go, especially when the Sea is tempestuous. 

There are Tempests and Hurricanes in the life of man. It is Prudence to put into a Haven, to let them blow over. Most commonly the Remedies increase the Evil. When the Sea of humours is in agitation, let Nature work; if it be the Sea of Manners, leave it to Morality. There is as much skill required in a Physician, in not prescribing, as in prescribing; and sometimes the excellency of the Art consists in applying no Remedy. The way then to calm popular gusts, is to be quiet. Then to yield to the times, will get the victory afterwards. A Well will be troubled if it be in the least stirred, and its water becomes clear again, by ceasing to dabble in it. There is no better remedy for some disorders, than to let them alone. For at long run they stop of themselves.

Gracian,  Oráculo, French translation: « L'homme de cour »

L’art de laisser aller les choses comme elles peuvent, surtout quand la mer est orageuse.

Il y a des tempêtes et des ouragans dans la vie humaine; c’est prudence de se retirer au port pour les laisser passer. Très souvent les remèdes font empirer les maux. Quand la mer des humeurs est agitée, laissez faire la nature ; si c’est la mer des mœurs, laissez faire la morale. Il faut autant d’habileté au médecin pour ne pas ordonner que pour ordonner ; et quelquefois la finesse de l’art consiste davantage à ne point appliquer de remède. Ce sera donc le moyen de calmer les bourrasques populaires, que de se tenir en repos ; céder alors au temps fera vaincre ensuite. Une fontaine devient trouble pour peu qu’on la remue, et son eau ne redevient claire qu’en cessant d’y toucher. Il n’y a point de meilleur remède à de certains désordres que de les laisser passer, car à la fin ils s’arrêtent d’eux-mêmes.

Gracian, Oráculo

Arte de dexar estar. 

Y más quando más rebuelta la común mar, o la familiar. Ai torbellinos en el humano trato, tempestades de voluntad; entonces es cordura retirarse al seguro puerto del dar vado. Muchas vezes empeoran los males con los remedios. Dexar hazer a la naturaleza allí, y aquí a la moralidad. Tanto ha de saber el sabio médico para recetar como para no recetar, y a vezes consiste el arte más en el no aplicar remedios. Sea modo de sossegar vulgares torbellinos el alçar mano y dexar sossegar; ceder al tiempo aora será vencer después. Una fuente con poca inquietud se enturvia, ni se bolverá a serenar procurándolo, sino dexándola. No ai mejor remedio de los desconciertos que dexallos correr, que assí caen de sí proprios.