impelling it in that direction. Not only the past intellectual success but the future hope of mankind lie in the fact that the mind is endowed with an appetite. The satisfaction of this mental appetite is, with the single exception next to be noted, the highest, most enduring, and most profitable of all human enjoyments. It is a solace which all may find, a luxury which never surfeits or reacts unfavorably, a passion whose unlimited indulgence is always safe. For all these reasons the volume of enjoyment thus derived is greater than that derived from any of the sources hitherto considered.
But there is one still higher pleasure, the most exalted of all. This is the discovery of truth. Sweet as may be this receptive process,—the act of intellectual conception—, the productive or reproductive process—the act of intellectual parturition—is yet sweeter. The raw materials that have been received into the mind through all the senses, the results of experience and education, undergo a process of gestation, as it were, and are developed into new shapes. To drop the figure, the innumerable items of acquired knowledge are brought into relations with one another, compared, combined, and organized into conceptions of varying degrees of generality. Truth is the recognition of identity under varying aspects. The mind devotes itself to the discovery of truth amidst all the manifold elements of its stored materials. This is the highest form of thinking. The identities are usually between the higher psychic units. The primary psychic unit is simple perception, but it is not until a multitude of registered perceptions have been organized into units of higher degrees that the process of identification begins. The higher the degree of the units the greater their resemblance to one another, and very complex psychic units are perceived to be all closely related. All knowing is a perception of relations, and this highest form of knowing is the perception of the relations that subsist among the largest psychic aggregates. This may take the form of generalization and be a classification of such aggregates. The truth then discovered is the position of the various conceptions in the hierarchy. But these conceptions are
