(Scientia), in its strictest sense, is a body of organized knowledge, whose phenomena are arranged so as to exhibit the reasons or causes by which they are influenced, in their legitimate connection and interdependence. That science which deals with the succession of reason and consequent, is entitled an abstract science; while that which deals with causes and effects is called, for the most part, a natural or physical science. Those sciences which are supposed to be complete are called exact sciences, such as geometry. But the great majority of what are called sciences—that is, all those branches of knowledge in which discovery is possible—hardly deserve the name, being only a bundle of theories or of facts, bound together with more or less exactness, and which a fresh discovery may any day untie. Science not only sees, and sees with certainty, but the distinguishing characteristic of it is, that it foresees. Thus it is distinguished from art. It is distinguished again from literature, in so far as it is its business to discover and apply self-evident principles.

The various sciences will be found under their appropriate heads throughout the work.