It is a fact of experience that men think. The object or suggestion is furnished by facts, and we then derive the concept instinctively. Thus, to analyze the faculty of thought means to find that which is common or general to the various personal and temporary processes of thought. In order to follow this study by the methods of natural science, we require neither physical instruments nor chemical reagents. The sense perception which is indispensable for every scientific understanding, is so to say present in this case _a priori_, without further experience. Every one possesses the object of our study, the fact of thought faculty and its experience, in the memories of himself or herself. We have seen that thought like any other activity as well as its scientific analysis is everywhere developing the general or abstract out of particular and concrete sense perceptions. We now express this in the following words: The common feature of all separate thought-processes consists in their seeking the general character or unity which is common to all objects experienced in their manifold variety by sense perceptions. The general element which is common to the different animals, or to the different manifestations of light, is that which constitutes the general animal or light concept. The general is the nature of all concepts, of all understanding, all science, all thought processes. Thus we arrive at the understanding that the analysis of the faculty of thought reveals its nature of finding that which is general and common to concrete and distinct things. The eye studies the visible, the ear the audible, and our brain that which is generally conceivable. We have seen that thought like any other activity requires an object; that it is unlimited in the choice of its objects, because all things may become the objects of thought; that these objects are perceived in manifold forms by various senses; and that they are transformed into simple ideas by extricating that which they possess in common, which is similar, which is general in them. If we apply this experienced understanding of the general method of thought processes to our special object, the faculty of thought, we realize that we have thus solved our problem, because all we were looking for was the general method of the thought process. _If the development of the general out of the concrete constitutes the general method by which reason arrives at understanding, then we have fully grasped reason as the faculty of deriving the general out of the concrete._