series of dates is relatively easy. One knows exactly where one is, and can keep track of one's progress and test one's success. Some people are attracted by such a task and are perfectly happy to follow this plan of study. The kind of mind that contents itself with such phonographic records, however, must be acknowledged to be a commonplace sort of affair. We recognize its limitations in ordinary life, invariably rating it lower than the mind that can reason to new conclusions and work independently. Accordingly, if we wish to possess minds of superior quality, we see that we must develop the reasoning processes. When we examine the mental processes by which we think constructively, or, in other words, reason, we find first of all that there is recognition of a problem to be solved. When we start to reason, we do it because we find ourselves in a situation from which we must extricate ourselves. The situation may be physical, as when our automobile stops suddenly on a country road; or it may be mental, as when we are deciding what college to attend. In both cases, we recognize that we are facing a problem which must be solved. After recognition of the problem, our next step is to start vigorous efforts to solve it. In doing this, we cast about for means; we summon all the powers at our disposal. In the case of the automobile, we call to mind other accidents and the causes of them; we remember that once the spark-plug played out, so we test this hypothesis. At another time some dust got into the carburetor, so we test this. So we go on, calling up possible causes and applying appropriate remedies until the right one is found and the engine is started. In bringing to bear upon the problem facts from our past experience, we form a series of judgments. In the case of the problem as to what college to attend, we might form these judgments: this college is nearer home; that one has a celebrated faculty; this one has good laboratories; that one is my father's alma mater. So we might go on, bringing up all the facts regarding the problem and fitting each one mentally to see how it works. Note that this utilization of ideas should not consist merely of fumbling about in a vague hope of hitting upon some solution. It must be a systematic search, guided by carefully chosen ideas. For example, "if the clock on the mantle-piece has stopped, and we have no idea how to make it go again, but mildly shake it in the hope that something will happen to set it going, we are merely fumbling. But if, on moving the clock gently so as to set the pendulum in motion, we hear it wobbling about irregularly, and at the same time observe that there is no ticking of any kind, we come to the conclusion that the pendulum has somehow or other escaped the little catch that connects it with the mechanism, we have been really thinking. From the fact that the pendulum wobbles irregularly, we infer that it has lost its proper catch.