INVENTION DEFINED. 311 CHAPTER I. NATURE OF INVENTION, AND SOME GENERAL RULES. 1. Definition.-INVENTION in Rhetoric is, primarily, the process by which an author obtains the material to be used, and devises and perfects the forms which he will employ to accomplish his purpose. Invention, secondarily, teaches how to choose subjects upon which to speak or write, how to gather material, and how to execute his purposes with it. 2. Mill's Description of Invention. John Stuart Mill, in his excellent work on Logic,* states the truth on this subject forcibly, so far as it applies to Induction. The same principle applies to all Invention. "Invention, though it can be cultivated, can not be reduced to rule; there is no science which will enable a man to bethink himself of that which will suit his purpose. But when he has thought of something, science will tell him whether that which he has thought of will suit his purpose or not." We may add here, that there is no science which will teach a man how to form a purpose. He must have that spontaneously, or growing out of circumstances which may be to prove a truth, to disseminate a doctrine, to produce a conviction, to lead to or prevent some action, or to amuse, etc. But when the purpose is formed, and what will suit his purpose is * Vol. i. p. 311 (London, 1856). suggested to his mind, both may be matured and perfected by science. Mr. Mill adds: "The inquirer or arguer must be guided by his own knowledge and sagacity in the choice of his inductions out of which he will construct his argument. But the validity of the argument, when constructed, depends on principles, and must be tried by tests which are the same for all inquiries." According to the same principle we may add, that the propriety of using any figure of speech, any particular mode of composition, must be decided, consciously or unconsciously, properly or improperly, by the laws of Rhetoric. 3. Rules can not exhaust the Subject.-It is plainly impossible to lay down rules upon this subject that shall embrace it entirely, for genius is ever striking out new paths. On this account, probably, many treatises on Rhetoric omit the subject of Invention entirely, and others make no attempt to present what can be of any practical value. We present a few general rules which should guide in Invention. 4. The First Rule.-The writer or speaker should in all cases, before proceeding to his work, form a definite idea of what he intends to accomplish. It may be that his circumstances already give him a specific purpose. Is he called upon to defend a certain proposition, to advocate a certain project, to describe a certain object, or to accomplish any other specific end? His powers of invention will at once be aroused and directed by that act. If he has no definite end in view except simply to |