VIII. Every political negotiation, may be compared to a machine, composed of many wheels, every one of which, by being more rigid, or more pliant, than is consistent with its just proportion, renders the whole machine useless; or it may be compared to a chemical process of long duration, whose success depends upon the different degrees of heat, to be applied with great nicety and precision, in the different stages of the process. But all the books that were ever written, either upon chemistry or mechanics, can never teach how to preserve this exact proportion of rigidity or pliability in the metals, or to apply this nice degree of heat to the fire, which is necessary for the completion of the business, and to answer the purposes intended. Even in these material operations, where the most nice and delicate parts of them, and the ultimate degree of exactitude in their execution, must be confided to a gift or innate talent in the artificer, we find that precepts are unequal to teach their performance; how then in political ones, where there is neither rule nor limits to determine their extension, their degrees of suspension, delay, or acceleration, with a thousand other contingent circumstances, can modes be prescribed for their execution? SECT. II. IX. The impossibility of imitating political examples, will be found still more manifest, if we consider, besides the person who acts, the people he is to act with. What is it to the purpose, that such an ambassador, has negotiated perfectly well at such a court, by employing such means? This example will be of no use to another ambassador, because, abstracted from an infinite number of other circumstances, a repetition of whose perfect assemblage will scarce ever happen, he does not negotiate with the same ministers; and every different genius, has a different door, through which you must enter to have access to his spirit.