Mind may justly be called a unity. But it is not a simple, indescribable unity, a unitary something separable from the sum of the parts of which it consists. It is, rather, a unity comparable to the unity of an animal organism or a plant, which may be well described as consisting of so many different parts functioning together according to definite laws. Within the unity of the mind there are smaller groups which may also be called unities, though in a restricted sense. The _I_ is one of these subordinate unities. It, too, is not simple, but consists of parts, sometimes a greater, sometimes a smaller number. It may expand and include almost as much content as mind itself, provided that time is given for such an expansion, and a sufficient stimulus. Usually the _I_ is very poor in content, hardly anything else than the word-idea which is the representative of the whole concept. 3. _Intelligence_ It is but natural that thought is largely in harmony with the actual facts. Its contents are derived from sensory experiences, are molded by sensory experiences, and must therefore often be anticipations of sensory experiences. With reference to its agreement or disagreement with the actual facts, we give our thought the name of truth, knowledge--or error. Both truths and errors, like perceptions and illusions, are the results of the laws governing mental functions. But truths are more common in the mental life of certain individuals than in that of others. Youth is more apt than mature age to give free rein to its imagination, no matter whether it agrees with reality or not. This is partly the result of the mature man’s realizing the high value of this agreement and therefore striving for it; partly the unintended consequence of innumerable pleasant and sad experiences, of adaptations which have proved now more, now less successful. But aside from such differences developing during life, there are immense differences of a similar kind resulting from native capacities. We speak of such capacities as reason, judgment, intelligence. Intelligence does not consist merely in a good memory, making possible the exact reproduction of experiences of long ago. A good memory in this sense contributes much toward a high degree of intelligence, but is not identical with it. Even the feeble-minded are often found to possess an astonishing capacity for retaining dates, poetry, music. But memory adapts the thought processes only to very simple and frequently recurring events. When the circumstances become complicated, it soon proves inadequate.