At two and three years of age, or as soon as a child begins to recognize and name new objects (because of their resemblance to things previously seen) this tendency to concept-building is manifest. Another illustration: The child has seen the family horse several times till the word horse becomes associated with that animal. While out walking it sees another horse, and pointing its finger says "horse." The memory of the first horse and the similarity calls forth the natural conclusion that this is a horse, though it may not be able to formulate the sentence. More horses are seen and compared till the word becomes the name of a whole class of animals. By a gradual process of observation, comparison, and judgment the word horse comes to stand for a large group of objects in nature.
A child's mind is naturally very _active_ in detecting resemblances and in grouping similar objects together. It notices that there are certain people called women, others called men; that certain animals are called sheep, others cattle. One class of objects receives the name book, another stove, etc. The work of observing, comparing, and classifying is a perpetual operation in the child's active moods. In this way, what may appear at first as an interminable confusion or blur of objects in nature begins to fall into groups and classes with appropriate names. It is the child's own way of bringing order out of the apparent chaos of his surroundings. All this process of classification is natural and nearly unconscious, and results in a better understanding and interpretation of the things around him.
Observe next the work of an educated _adult_, and how he increases and arranges his knowledge. If he is an incipient dry-goods merchant he learns by sight and touch to detect the quality of goods. He compares and classifies his experiences and becomes in time an expert in judging textile fabrics. On the other hand he becomes acquainted by personal contact with various customers and learns how to classify and judge them both as buyers and as debtors.
If a _botanist_ finds a new plant he examines its stem, leaves, root, flower, seed, and environment. While entering into these details he is also comparing it with familiar classes of plants. Finally, he is not satisfied till he can definitely locate it in his previous system. With every new plant that he discovers he travels over the whole road from the individual particulars to the general classes of his whole system. The merchant and the scientist follow out with painstaking care and industry the same course which was involuntarily taken by the child; namely, observation of particulars, comparing and grouping into classes. The same habit of mind may be observed in all people who are growing knowledgewards and who possess any thoughtful instincts. In building up concepts, especially with the adult, induction is constantly mingled with deduction. As fast as general notions are formed they are used to interpret new objects. As the amount of this organized and classified knowledge increases, we reason more and more deductively.
