The essentials of the thinking process are three: (1) a state of doubt or uncertainty, resulting in suspended judgment; (2) an organization and control of mental states in view of an end to be attained; (3) a critical attitude involving selection and rejection of suggestions offered. The recognition of some lack of adjustment, the feeling of need for something one hasn't, is the only stimulus toward thinking. This problematic situation, resulting in suspended judgment, caused by the inadequacy of present power or knowledge, may arise in connection with any situation. It is unfortunate that the terms "problematic situation" and "feeling of inadequacy" have been discussed almost entirely in connection with situations when the result has some pragmatic value. There is no question but what the situation arousing thinking must be a live one and a real one, but it need not be one the answer to which will be useful. It is true that with the majority of people, both children and adults, a problem of this type will be more often effective in arousing the thinking process than a problem of a more abstract nature, but it is not always so, nor necessarily so. Most children sometimes, and some children most of the time, enjoy thinking simply for the sake of the activity. They do not need the concrete, pragmatic situation--anything, no matter how abstract, that arouses their curiosity or appeals to their love of mastery offers enough of a problem. Sometimes children are vitally interested in working geometrical problems, translating difficult passages in Latin, striving to invent the perpetual motion machine, even though there is no evident and useful result. It is not the particular type of situation that is the thing to be considered, but the attitude that it arouses in the individual concerned. Educators in discussion of the situations that make for thinking must allow for individual differences and must plan for the intellectually minded as well as for others. The thinker confronted by a situation for which his present knowledge is not adequate, recognizes the difficulty and suspends judgment; in other words, does not jump at a conclusion but undertakes to think it out. To do this control is continually necessary. He must keep his problem continually before him and work directly for its solution, avoiding delays, avoiding being side-tracked. This means, of course, the critical attitude towards all suggestions offered. Each one as it comes must be inspected in the light of the end to be reached--if it does not seem to help towards that goal, it must be rejected. Criticism, selection, and rejection of suggestions offered must continue as long as the thinking process goes on. "To maintain the state of doubt and to carry on systematic and protracted inquiry--these are the essentials of thinking."