There is invention operating on great masses--social or political invention strictly so called--ordinarily not proposed but imposed, which, however, despite its coercive power, is subject to requirements even more numerous than mechanical, industrial, or commercial invention. It has to struggle against natural forces, but most of all against human forces--inherited habits, customs, traditions. It must make terms with dominant passions and ideas, finding its justification, like all other creation, only in success. Without entering into the details of this inevitable determination, which would require useless repetition, we may sum up the role of the constructive imagination in social matters by saying that it has undergone a regression--i.e., that its area of development has been little by little narrowed; not that inventive genius, reduced to pure construction in images, has suffered an eclipse, but on its part it has had to make increasingly greater room for experiment, rational elements, calculation, inductions and deductions that permit foresight--for practical necessities. If we omit the spontaneous, instinctive, semi-conscious invention of the earliest ages, that was sufficient for primitive societies, and keep to creations that were the result of reflection and of great pretension, we can roughly distinguish three successive periods: (1) A very long idealistic phase (Antiquity, Renaissance) when triumphed the pure imagination, and the play of the free fancy that spends itself in social novels. Between the creation of the mind and the life of contemporary society there was no relation; they were worlds apart, strangers to one another. The true Utopians scarcely troubled themselves to make applications. Plato and More--would they have wished to realize their dreams? (2) An intermediate phase, when an attempt is made to pass from the ideal to the practical, from pure speculation to social facts. Already, in the eighteenth century, some philosophers (Locke, Rousseau) drew up constitutions, at the request of interested persons. During this period, when the work of the imagination, instead of merely becoming fixed in books, tends to become objectified in acts, we find many failures and some successes. Let us recall the fruitless attempts of the "phalansteries" in France, in Algeria, Brazil, and in the United States. Robert Owen was more fortunate;[145] in four years he reformed New Larnak, after his ideal, and with varying fortune founded short-lived colonies. Saint-Simonism has not entirely died out; the primitive civilization after his ideal rapidly disappeared, but some of his theories have filtered into or have become incorporated with other doctrines.