was unknown. It might with propriety be called the philosophy of invention. During the early part of my residence in London, I commenced several essays on Induction, Generalization, Analogy, with various illustrations from different sources. The philosophy of signs always occupied my attention, and to whatever subject I applied myself I was ever on the watch to perceive and record the links by which the new was connected with the known.
Most of the early essays I refer to were not sufficiently matured for publication, and several have appeared without any direct reference to the great object of my life. I may, however, point out one of my earlier papers in the "Philosophical Transactions for 1817," which, whilst it made considerable additions to a new branch of science, is itself a very striking instance of the use of analogy for the purpose of invention. I refer to the "Essay on the Analogy between the Calculus of Functions and other Branches of Analysis."—Phil. Trans. 1817.
