Now, since every truth, which is not itself a first principle, becomes manifest from the truth of some first principle, it is therefore necessary in every inquiry to have a knowledge of the first principle involved, to which by analysis we may go back for the certainty of all the propositions which are afterwards accepted. And since this treatise is an inquiry, we must begin by examining the first principle on the strength of which deductions are to rest. It must be understood then that there are certain things which, since they are not subject to our power, are matters of speculation, but not of action: such are Mathematics and Physics, and things divine. But there are some things which, since they are subject to our power, are matters of action as well as of speculation, and in them we do not act for the sake of speculation, but contrariwise: for in such things action is the end. Now, since the matter which we have in hand has to do with states, nay, with the very origin and principle of good forms of government, and since all that concerns states is subject to our power, it is manifest that our subject is not in the first place speculation, but action. And again, since in matters of action the end sought is the first principle and cause of all (for that it is which first moves the agent to act), it follows that all our method concerning the means which are set to gain the end must be taken from the end. For there will be one way of cutting wood to build a house, and another to build a ship. That therefore, if it exists, which is the ultimate end for the universal civil order of mankind, will be the first principle from which all the truth of our future deductions will be sufficiently manifest. But it is folly to think that there is an end for this and for that particular civil order, and yet not one end for all. III.--Now, therefore, we must see what is the end of the whole civil order of men; and when we have found this, then, as the Philosopher[152] says in his book to Nicomachus,[153] the half of our labour will have been accomplished. And to render the question clearer, we must observe that as there is a certain end for which nature makes the thumb, and another, different from this, for which she makes the whole hand, and again another for which she makes the arm, and another different from all for which she makes the whole man; so there is one end for which she orders the individual man, and another for which she orders the family, and another end for the city, and another for the kingdom, and finally an ultimate one for which the Everlasting God, by His art which is nature, brings into being the whole human race. And this is what we seek as a first principle to guide our whole inquiry. [Footnote 152: The common title for Aristotle from the first half of the thirteenth century. _Vide_ Jourdain, _Recherches sur les traductions d'Aristote_, p. 212, note.] [Footnote 153: Arist. _Ethics_, i. 7.]