=C. By Inference, or Deduction.=--Again, knowledge about a particular individual, or particular knowledge, may be gained in what seems a yet more indirect way. For instance, instead of standing beside Socrates and seeing him drink the hemlock and die, and thus, by actual sense observation, learn that Socrates is mortal; we may, by a previous series of experiences, have gained the knowledge that all men are mortal. For that reason, even while he yet lives, we may know the particular fact that Socrates, being a man, is also mortal. In this process the person is supposed to start with the known general truth, "All men are mortal"; next, to call to mind the fact that Socrates is a man; and finally, by a comparison of these statements or thoughts, reason out, or deduce, the inference that therefore Socrates is mortal. This process is, therefore, usually illustrated in what is called the syllogistic form, thus: All men are mortal. Socrates is a man. Socrates is mortal. When particular knowledge about an individual thing or event is thus inferred by comparing two known statements, it is said to be secured by a process of _deduction_, or by inference. GENERAL KNOWLEDGE In all of the above examples, whether experienced through the senses, built up by an act of imagination, or gained by inference, the knowledge is of a single thing, fact, organism, or unity, possessing a real or imaginary existence. In addition to possessing its own individual unity, however, a thing will stand in a more or less close relation with many other things. Various individuals, therefore, enter into larger relations constituting groups, or classes, of objects. In addition, therefore, to recognizing the object as a particular experience, the mind is able, by examining certain individuals, to select and relate the common characteristics of such classes, or groups, and build up a general, or class, idea, which is representative of any member of the class. Thus arise such general ideas as book, man, island, county, etc. These are known as universal, or class, notions. Moreover, such rules, or definitions, as, "A noun is the name of anything"; "A fraction is a number which expresses one or more equal parts of a whole," are general truths, because they express in the form of a statement the general qualities which have been read into the ideas, noun and fraction. When the mind, from a study of particulars, thus either forms a class notion as noun, triangle, hepatica, etc., or draws a general conclusion as, "Air has weight," "Any two sides of a triangle are together greater than the third side," it is said to gain general knowledge. ACQUISITION OF GENERAL KNOWLEDGE