Politics is the science of always using the most convenient means in accord with one's own interests. In order to act in conformity with one's interests, one must know what these interests are, and in order to gain this knowledge, one must study their history and application . . . One must attempt, above all, to know the special genius of the people which one wants to govern in order to know if one must treat them leniently or severely, if they are inclined to revolt . . . to intrigue . . .
[The Prussian nobility] has sacrificed its life and goods for the service of the state; its loyalty and merit have earned it the protection of all its rulers, and it is one of the duties [of the ruler] to aid those noble families which have become impoverished in order to keep them in possession of their lands; for they are to be regarded as the pedestals and the pillars of the state. In such a state no factions or rebellions need be feared . . . it is one goal of the policy of this state to preserve the nobility.
A well conducted government must have an underlying concept so well integrated that it could be likened to a system of philosophy. All actions taken must be well reasoned, and all financial, political and military matters must flow towards one goal, which is the strengthening of the state and the furthering of its power. However, such a system can flow but from a single brain, and this must be that of the sovereign. Laziness, hedonism and imbecility, these are the causes which restrain princes in working at the noble task of bringing happiness to their subjects . . . A sovereign is not elevated to his high position, supreme power has not been confined to him in order that he may live in lazy luxury, enriching himself by the labor of the people, being happy while everyone else suffers. The sovereign is the first servant of the state. He is well paid in order that he may sustain the dignity of his office, but one demands that he work efficiently for the good of the state, and that he, at the very least, pay personal attention to the most important problems . . .
You can see, without doubt, how important it is that the King of Prussia govern personally. Just as it would have been impossible for Newton to arrive at his system of attractions if he had worked in harness with Leibnitz and Descartes, so a system of politics cannot be arrived at and continued if it has not sprung from a single brain . . . All parts of the government are inexorably linked with each other. Finance, politics and military affairs are inseparable; it does not suffice that one will be well administered; they must all be . . . a Prince who governs personally, who has formed his [own] political system, will not be handicapped when occasions arise where he has to act swiftly, for he can guide all matters towards the end which he has set for himself . . .
Catholics, Lutherans, Reformed, Jews and other Christian sects live in this state, and live together in peace. If the sovereign, actuated by a mistaken zeal, declares himself for one religion or another, parties spring up, heated disputes ensue, little by little persecutions will commence and, in the end, the religion persecuted will leave the fatherland, and millions of subjects will enrich our neighbors by their skill and industry.
It is of no concern in politics whether the ruler has a religion or whether he has none. All religions, if one examines them, are founded on superstitious systems, more or less absurd. It is impossible for a man of good sense, who dissects their contents, not to see their error; but these prejudices, these errors and mysteries, were made for men, and one must know enough to respect the public and not to outrage its faith, whatever religion be involved.
From: "Frederick II, Political Testament," in Europe in Review, eds. George L. Mosse et al. (Chicago: Rand MacNally, 1957), pp. 110-112. Reprinted in Dennis Sherman, ed., Western Civilization: Sources, Images, and Interpretations, Vol. II, (New York; McGraw-Hill, 1995) pp. 41-42