Eight years before his return to France, De Caus had published at Frankfort his Raison des Forces Mouvantes, a treatise in which he described "an apparatus for forcing up water by a steam fountain," which differs only in one particular from that of Della Porta. The apparatus seems never to have been constructed, but Arago, relying on the description, has named De Caus the inventor of the steam engine.
It is not, however, with the inventive genius that we are concerned, but with the ill-starred lover of Marion Delorme. The minister Particelli took De Caus one day to the petit lever of the brilliant and beautiful Aspasia of the Place Royale. Particelli, one of the most prodigal of her adorers, wanted De Caus to surpass, in the palace of Mademoiselle Delorme, the splendours he had achieved in the palace of the Prince of Wales. "At my charge, look you, Monsieur Salomon, and spare nothing! Scatter with both hands gold, silver, colours, marble, bronze, and precious stuffs—what you please. Imagine, seek, invent,—and count on me!"
But Monsieur Salomon had no sooner seen the goddess of Particelli than he too was lifted from the earth and borne straight into the empyrean. At the moment of leaving her, when she suffered him to kiss her hand, and let him feel the darts of desire which shot from those not too prudish eyes, Salomon de Caus "devint amoureux à en perdre la tête." Thenceforth, in brief,
"His chief good and market of his time"
was to obey and anticipate every wild and frivolous fantasy of Marion Delorme. Michel Particelli's hyperbolical commission should be fulfilled for him beyond his own imaginings! He threw down the palace of Marion and built another in its place. The new palace was to cede in nothing to the Louvre or Saint-Germain. With his own hands Salomon de Caus decorated it; and then, at the bidding of his protector, Particelli, he consented, bon grè, mal grè, to paint the picture of the divinity herself.
"Alone one morning with his delicious model," the distracted artist flung brushes and palette from him, and cast himself at her feet. "Mon cœur se déchire, ma tête se perd.... Je deviens fou, je vous aime, et je me meurs!" It was a declaration of much in little, and Marion, a connaisseuse of such speeches, absolved and accepted him with a kiss.
Installed by right of conquest in that Circean boudoir, which drew as a magnet the wit and gallantry of Paris, Salomon stood sentinel at the door "like a eunuch or a Cerberus." Brissac and Saint-Evremont received the most Lenten entertainment, and the proposals of Cinq-Mars were rejected. Marion was even persuaded to be not at home to Richelieu himself. But the happy Salomon grew unhappy, and more unhappy. Every moment he came with a sigh upon some souvenir, delicately equivocal, of the vie galante of his mistress; and when love began to feed upon the venom of jealousy, his complacent goddess grew capricious, vexed, irritated, and at length incensed. After that, she resolved coldly on Salomon's betrayal. It was the fashion of the age to be cruel in one's vengeance. Marion penned a note to Richelieu:
"I want so much to see you again. I send with this the little key which opens the little door.... You must forgive everything, and you are not to be angry at finding here a most learned young man whom the love of science and the science of love have combined to reduce to a condition of midsummer madness. Does your friendship for me, to say nothing of your respect for yourself, suggest any means of ridding me instantly of this embarrassing lunatic? The poor devil loves me to distraction. He is astonishingly clever, and has discovered wonders—mountains that nobody else has seen, and worlds that nobody else has imagined. He has all the talents of the Bible, and another, the talent of making me the most miserable of women. This genius from the moon, whom I commend to your Eminence's most particular attention, is called Salomon de Caus."
A missive of that colour, from a Marion Delorme to a Richelieu, was the request polite for a lettre de cachet. Salomon de Caus was invited to call upon the Cardinal. Behind his jealous passion for his mistress, Salomon still cherished his passion for science, and he went hot-foot to Richelieu with his hundred schemes for changing the face of the world, with steam as the motive power. It must have been a curious interview. At the end, Richelieu summoned the captain of his guard.
"Take this man away."