This search for an ideal security has had its influence on philosophy. Many philosophers, from the time of the ancient Greeks till now, have sought to construct systems of ideas, verbal forms in which in contemplation they could find refuge from the universal change in which all things come and pass away. Inasmuch as it is possible to think of an object or class and to mean the same even when the objects themselves are no longer present, a system of abstract and unusual universal ideas is set up and thought of as existing in itself, outside the process of time and change. The system of thought so conceived is held to be more enduring than the world of changing objects. The ideal world is then the real world. In it alone is knowledge of the Truth which abides forever. Such systems appear to me to be elaborate attempts to sustain a fictitious security by taking refuge from reality in a logical arrangement of man’s own empty forms of thought. From the point of view of education it should be said that such philosophies require much learning before one can understand them, but they tend to dogmatism and the closed mind. A modern method of supporting the fiction of security--less austere and sophisticated than some of those of official philosophy--prevails among those who speak the language of science. It is known as mechanism. As scientific _method_, mechanism is indispensable. It is found by exact measurement and careful scrutiny that given two identical material situations, the same result will follow. There is a certain orderliness about the processes of nature, which if we ignore all else but the movement and masses and temporal and spatial relationships of particles of matter, lends itself to statement in mathematical terms. In this manner events are predictable with great accuracy. And now because it becomes possible for human reason to interpret facts of nature when they are thought of only with respect to mass, movement, position, it is held that nature itself is really nothing but mass, motion, position, etc. The laws and methods of interpretation are thought to constitute the nature of that which is interpreted. A method deliberately adopted in order to give a mathematically rational account of certain selected aspects of nature is now taken for a correct picture of ultimate reality. The reason which measures masses and distances believes it has discovered itself as the true nature of the thing measured. The universe is held to be at once like a machine, and at the same time essentially rational. Security is again grounded in forms of thought.