A decorative headband featuring floral and scroll motifs sits at the top of the page. The initial letter 'S' is a large, historiated drop cap, intricately decorated with a human figure and foliage.

TO THE KING

MOST CHRISTIAN

The "Most Christian King" (original: "Roy Tres-Chrestien") was the traditional title for the Kings of France.

Sire,

After having completed this present book, which treats the principles of motive forces and various machines, I doubted whether said book deserved to be dedicated to Your Majesty. This is because some might think that this art is more suited to craftsmen than to a King, who ought instead to employ his time in governing his subjects well, in fearing God so as to set a general example, and in making himself feared by his enemies. These three things are greatly required of a Prince, for they are the three pillars that sustain his State.

Furthermore, to govern such a large number of people, it is well that he should not only be assisted by a number of people versed in all sorts of arts and sciences, but also that he himself be somewhat knowledgeable, especially in the mathematical sciences and those which depend upon them. This is to the end that he may not be subject to believing any flatterers who, seeing a Prince ignorant of these matters when an occasion for some work presents itself, make him believe something entirely different from how the work can actually succeed; so much so that this sometimes turns to the shame and displeasure of the said Prince.

Vitruvius Marcus Vitruvius Pollio was a Roman architect and engineer whose works were rediscovered during the Renaissance, becoming the foundation for classical architecture., an excellent Architect of his time, mentions in the Epistle of his second book, addressed to the Emperor Julius Caesar, that the Architect Dinocrates of Macedonia—a man endowed with a fine physical presence and lofty imagination—came to find Alexander the Great. He represented to him through his discourse that he had formed an idea to shape Mount Athos into the likeness of a statue of a man, which would hold a spacious city in its left hand, and in its right, a bowl that would receive all the rivers from the surrounding mountains and from there discharge them into the sea. Alexander found the design very beautiful, but considering the difficulty there would be in bringing food to said city, as the surrounding country was very sterile, he would not hear of it. Later, he had the city of Alexandria built by the same Architect, which still stands today. Thus, Alexander’s judgment surpassed that of Dinocrates, in that this great work would have been made in vain.

Princes are often solicited by such Architects and engineers (rather full of vain imaginations than of good foundations) to have them undertake works which can bring neither utility nor pleasure. Thus, when said Princes are somewhat knowledgeable, they can clearly see through these designs that the work cannot be done according to these imaginations.

All these reasons, Sire, have given me the boldness to present to you this book, where in seven or eight leaves the principles of motive forces are represented as briefly and succinctly as has been possible for me. Following these are several machines, some useful and others pleasant. Among the others, Your Majesty will be able to recognize some which can be moved solely by means of the temperature of the air—which, coming to be heated by means of the Sun, or cooling by its absence, animates the said machines. By this means, one can do admirable things. If I can understand that Your Majesty takes some pleasure in this small work of mine, it will give me the courage to augment it with several other fine designs. May it please Your Majesty, therefore, to accept it favorably, until I have the means to serve you in greater things. I pray God to grant me this grace, and to you, Sire, to be maintained in His holy protection and to be filled with His graces.

From Heidelberg, this 15th of February, 1615.

Salomon de Caus (1576–1626) was a French Huguenot engineer and architect whose work was influential in the development of hydraulics and early steam power.