Almost as soon as he obtained a commission in the French army he followed Lafayette to America and when, after four years, fighting ceased, he bade farewell to his profession. Even before this we find him dreaming of piercing the Isthmus of Panama. A little later he offered his services in Holland for an expedition against the British Indies and was also concerned more concretely with projects for building canals in Spain. The Revolution found him back in Paris, as the citoyen Bonhomme, forswearing his title and acting the extreme Sansculotte. But soon more profitable ventures offered themselves. In the sale of the church lands we find him as one of the most active intermediaries, speculating with borrowed money on a colossal scale, one of the great profiteers of inflation, who did not scorn any business that came his way, such as an attempted sale of the lead from the roofs of Notre Dame. It is not surprising to find him in prison during the Terror. It was during the time he spent there that according to his own account he decided on the career of a philosopher. But, released, he once more preferred financial to metaphysical speculation. So long as the source of his funds (a Saxon diplomatist) continued to provide him with sufficient capital, he tried his hand at all sorts of commercial ventures, such as organizing a stage coach service, selling wine retail, manufacturing textiles and even ``republican'' playing cards in which the obnoxious kings and queens were replaced by le génie and la liberté. His plans were even more ambitious. He seems to have begun the construction of some large industrial plant and he at least contemplated a combined commercial and banking enterprise that ``should be unique in the world.'' He also acted as spokesman for French financial interests at the Anglo-French discussions at Lille in 1797.
All these activities, however, came to a sudden end when in 1798 his partner returned to Paris and asked to be shown the accounts. Saint-Simon certainly knew what high living meant, and his house, run by the former maître d'hôtel of the Duc de Choiseul, and his kitchen, presided over by an equally reputed chef, were famous. But that all the costs of this should have gone down as expenses on the joint account rather upset the good Saxon count. He withdrew his funds, and Saint-Simon, still in possession of a fortune, substantial but no longer adequate to support further grandiose ventures, found it advisable to withdraw from commercial activity and henceforth to seek glory in the intellectual sphere.
We need not doubt that in the mind of the disappointed faiseur vague plans for the reorganization of society were already forming; and it is not surprising that he should soon find that all his experiences had not provided him with the knowledge which would enable him to elaborate these ideas. He therefore decided ``to employ his money to acquire scientific knowledge.''12.3 It was at this time that he spent three years in close contact with the teachers and students of the Ecole polytechnique as a kind of Maecenas-pupil, feasting the professors and assisting the students, one of whom, the great mathematician Poisson, he entirely supported for years and treated as his adopted son.
The method of study which Saint-Simon chose for himself was not of the ordinary. Feeling that his brain was no longer elastic enough to pursue a systematic course, he preferred to learn what he could in the more pleasant form of dinner-table conversation. He asked the scholars from whose knowledge he hoped to profit to his house, and appears even to have married for the sole purpose of keeping a house where he could properly entertain the great savants. Lagrange, Monge, Berthollet, and, probably after 1801, when he felt he had completed his education in the mechanical sciences and moved to the neighborhood of the Ecole de médecine, Gall, Cabanis, and Bichat, are reported to have partaken of his hospitality. Yet this method of study seems to have proved to be of questionable value. At any rate in later life our hero complained to a friend that his ``scholars and artists ate much but talked little. After dinner I went to sit in an easy chair in a corner of the salon and fell asleep. Fortunately Madame de Saint-Simon did the honneurs with much grace and esprit,''12.4
Whether it was merely that he became aware that this had been a bad investment and decided to cut the losses, or whether it was that another marriage appeared to him a more attractive method of instruction, not only the dinners but also the marriage came to an end soon after he had moved to the new place. He explained to his wife that ``the first man of the world ought to be married to the first woman'' and that, therefore, with much regret he had to ask her to be released. Was it an accident that the divorce was effected in the month after Madame de Staël had become a widow, the Madame de Staël who, in a book that had fired Saint-Simon's imagination, had only just celebrated the ``positive sciences'' and emphasized that the ``science of politics was yet to be created?''12.5 It is alleged that as soon as he was free he hurried to Le Coppet on the Lake of Geneva and proposed in the following words: ``Madame, you are the most extraordinary woman on earth and I am the most extraordinary man; together we shall undoubtedly produce a still more extraordinary child.'' Legend adds that he also proposed that they should celebrate their nuptials in a balloon. About the terms in which the refusal was couched the versions vary.