As in mathematical creations figures are formed on distinct formulæ, which are the laws under which they are developed, so it is in ethical and political subjects. Doctrines expand variously according to the mind, individual or social, into which they are received; and the peculiarities of the recipient are the regulating power, the law, the organization, or, as it may be called, the form of the development. The life of doctrines may be said to consist in the law or principle which they embody. Principles are abstract and general, doctrines relate to facts; doctrines develope, and principles at first sight do not; doctrines grow and are enlarged, principles are permanent; doctrines are intellectual, and principles are more immediately ethical and practical. Systems live in principles and represent doctrines. Personal responsibility is a principle, the Being of a God is a doctrine; from that doctrine all theology has come in due course, whereas that principle is not clearer under the Gospel than in paradise, and depends, not on belief in an Almighty Governor, but on conscience. Yet the difference between the two sometimes merely exists in our mode of viewing them; and what is a doctrine in one philosophy is a principle in another. Personal responsibility may be made a doctrinal basis, and develope into Arminianism or Pelagianism. Again, it may be discussed whether infallibility is a principle or a doctrine of the Church of Rome, and dogmatism a principle or doctrine of Christianity. Again, consideration for the poor is a doctrine of the Church considered as a religious body, and a principle when she is viewed as a political power. Doctrines stand to principles, as the definitions to the axioms and postulates of mathematics. Thus the 15th and 17th propositions of Euclid's book I. are developments, not of the three first axioms, which are required in the proof, but of the definition of a right angle. Perhaps the perplexity, which arises in the mind of a beginner, on learning the early propositions of the second book, arises from these being more prominently exemplifications of axioms than developments of definitions. He looks for developments from the definition of the rectangle, and finds but various particular cases of the general truth, that "the whole is equal to its parts." 2. It might be expected that the Catholic principles would be later in development than the Catholic doctrines, inasmuch as they lie deeper in the mind, and are assumptions rather than objective professions. This has been the case. The Protestant controversy has mainly turned, or is turning, on one or other of the principles of Catholicity; and to this day the rule of Scripture Interpretation, the doctrine of Inspiration, the relation of Faith to Reason, moral responsibility, private judgment, inherent grace, the seat of infallibility, remain, I suppose, more or less undeveloped, or, at least, undefined, by the Church.