The encyclopaedia of philosophy must not be confounded with ordinary encyclopaedias. An ordinary encyclopaedia does not pretend to be more than an aggregation of sciences, regulated by no principle, and merely as experience offers them. Sometimes it even includes what merely bear the name of sciences, while they are nothing more than a collection of bits of information. In an aggregate like this, the several branches of knowledge owe their place in the encyclopaedia to extrinsic reasons, and their unity is therefore artificial: they are _arranged,_ but we cannot say they form a _system._ For the same reason, especially as the materials to be combined also depend upon no one rule or principle, the arrangement is at best an experiment, and will always exhibit inequalities. An encyclopaedia of philosophy excludes three kinds of partial science. I. It excludes mere aggregates of bits of information. Philology in its _prima facie_ aspect belongs to this class. II. It rejects the quasi-sciences, which are founded on an act of arbitrary will alone, such as Heraldry. Sciences of this class are positive from beginning to end. III. In another class of sciences, also styled positive, but which have a rational basis and a rational beginning, philosophy claims that constituent as its own. The positive features remain the property of the sciences themselves. The positive element in the last class of sciences is of different sorts. (I) Their commencement, though rational at bottom, yields to the influence of fortuitousness, when they have to bring their universal truth into contact with actual facts and the single phenomena of experience. In this region of chance and change, the adequate notion of science must yield its place to reasons or grounds of explanation. Thus, _e.g._ in the science of jurisprudence, or in the system of direct and indirect taxation, it is necessary to have certain points precisely and definitively settled which lie beyond the competence of the absolute lines laid down by the pure notion. A certain latitude of settlement accordingly is left: and each point may be determined in one way on one principle, in another way on another, and admits of no definitive certainty. Similarly the Idea of Nature, when parcelled out in detail, is dissipated into contingencies. Natural history, geography, and medicine stumble upon descriptions of existence, upon kinds and distinctions, which are not determined by reason, but by sport and adventitious incidents. Even history comes under the same category. The Idea is its essence and inner nature; but, as it appears, everything is under contingency and in the field of voluntary action. (II) These sciences are positive also in failing to recognise the finite nature of what they predicate, and to point out how these categories and their whole sphere pass into a higher. They assume their statements to possess an authority beyond appeal. Here the fault lies