The practice and the spirit of justice pervade every highly developed social grouping, such as marriage, friendship, or fellow-citizenship in a democracy. For Aristotle a friendship is "one {106} soul dwelling in two bodies";[20] that is, the same high capacity uniting two individuals in the acknowledgment of its common principles, and in the contemplation of its common objects. Aristotle's other saying, that "man is a political animal," is inspired with the same meaning. To participate in the life of a state, in which one's fellow-citizens were one's equals, in which men with equal endowments carried on one united activity while acknowledging one another's independence, was to an Athenian the very fulness of life. To be banished from it was, even in the eyes of the law, equivalent to death. In a chapter of his _Physics and Politics_, entitled "The Age of Discussion," Bagehot has admirably represented the importance for human progress of an open exchange of opinion on all matters of great consequence: In this manner all the great movements of thought in ancient and modern times have been nearly connected in time with government by discussion. Athens, Rome, the Italian republics of the Middle Ages, the communes and states-general of feudal Europe, have all had a special and peculiar quickening influence, which they owed to their freedom, and which states without that freedom have never communicated. And it has been at the time of great epochs of thought--at the Peloponnesian War, at the fall of the Roman Republic, at the Reformation, at the French Revolution--that such liberty of speaking and thinking have produced their full effect.[21] {107} Elsewhere Bagehot attributes to freedom of discussion, not only the deliverance from narrow and conventional habits, but that general elevation of tone which is characteristic of such an era as the Elizabethan age in England. In short, justice or toleration, since it encourages men to push on to the limit of their powers, promotes not only originality and diversity, but a love of perfection. It will have been observed that justice and freedom are complementary, for he who is just liberates, and he who is free receives justice. Together they constitute the basis of all the higher relationships between men, of a progressive society, and of the whole constructive movement which we call civilization.