Without thinking, man would be dependent upon each particular experience for his knowledge, except so far as memory and imagination could instinctively aid him. By thought processes he is enabled to infer that if certain things be true of one of a certain kind of things, the same thing may be expected from others of the same class. As he is able to note points of likeness or difference, he is able to form clearer and truer inferences. In addition, he is able to apply his constructive imagination to the rearrangement and recombination of things whose nature he has discovered, and thus progress along the line of material achievement as well as of knowledge. It must be remembered, however, that the intellect depends entirely for its material upon the perception, which in turn receives its raw material from the senses. The intellect merely groups together the material of perception, makes inferences, draws conclusions from, and forms conclusions regarding, them, and in the case of constructive imagination recombines them in effective forms and arrangement. The intellect is the last in order in the course of mental evolution. It appears last in order in the mind of the child, but it often persists in old age after the feelings have grown dim and the memory weak. CONCEPTS. What is known as the "concept" is the first fruit of the elemental processes of thought. The various images of outside objects are sensed, then perceived, and then grouped according to their likenesses and differences, and the result is the production of concepts. It is difficult to define a concept so as to convey any meaning to the beginner. For instance, the dictionaries give the definition as "an abstract, general conception, idea, or notion formed in the mind." Not very clear this, is it? Perhaps we can understand it better if we say that the terms dog, cat, man, horse, house, etc., each expresses a concept. Every term expresses a concept; every general name of a thing or quality is a term applied to the concept. We shall see this a little clearer as we proceed. We form a concept in this way: (1) We _perceive_ a number of things; (2) then we notice certain _qualities_ possessed by things--certain properties, attributes, or characteristics which make the thing what it is; (3) then we _compare_ these qualities of the thing with the qualities of other things and see that there is a likeness in some cases, in various degrees, and a difference in other cases, in various degrees; (4) then we _generalize_ or _classify_ the perceived things according to their ascertained likenesses and differences; (5) then we form a _general idea_ or _concept_ embodying each class of thing; and, finally, we give to the concept a _term_, or _name_, which is its symbol.