he has made something true which before was not true, but that he has discovered what always was true, although until the discovery he did not know it. To this the pragmatist reply is, that this very belief is a practical consequence involved in the verification of the hypothesis, involved in the discovery that it works. What he denies is that truth reveals, or ever can reveal, a reality entirely irrelevant to any human purpose. It is also very important to add that in declaring that truth is verification, the {48} pragmatist does not set up a purely practical or utilitarian standard. The "working" of truth means theoretical as well as practical working. Much of the current criticism of pragmatism has failed to take notice of this intention or meaning of its principle, and hence the common misapprehension that the maxim "truth is what works" must mean that whatever a man believes is for him truth. The pragmatist doctrine and attitude will perhaps be easier to understand if we take it in regard to a particular instance of truth and error in regard to fundamental notions. In the last four or five years a new principle has been formulated in Physics, named the Principle of Relativity. It revolutionises the current conceptions of space and time. It is so recent that probably some of my readers now hear of it for the first time, and therefore before I refer to its formulation by mathematicians I will give a simple illustration to explain what it is. Suppose that you are walking up and down the deck of a steamer, and let us suppose that the steamer is proceeding at the speed of four miles an hour, the space that you cover and the interval of time that you occupy are exactly the same for you whether you are moving up the deck in the direction the steamer is going or down the deck in the direction which is the reverse of the steamer's movement. But suppose some one on the shore could observe you moving while the ship was invisible to him, your movement would appear to him entirely different to what it is to you. When you were walking up the deck you would seem to be going at twice the speed you would be going, and when you were going down the deck you would seem not to be moving at all. The time measurement would also seem different to the observer on the shore, for while to you each moment would be measured by an equal {49} space covered, to him one moment you would be moving rapidly, the next at rest. This is simple and easy to understand. Now suppose that both you and the observer were each observing a natural phenomenon, say a thunder-storm, it would seem that each of you ought to observe it with a difference--a difference strictly calculable from the system of movement, the ship, in which you were placed in relation to him. The propagation of the sound and of the light would have to undergo a correction if each of you described your experience to the other. If you were moving in the direction of the light waves they would be