An illustration may make the matter clearer: A boy walking along in the woods comes to a stream too wide for him to jump across. He wishes to be on the other side, so here is a situation that must be met, a problem that must be solved. A flow of ideas is started centering about the problem. The flow is entirely determined and directed by past experience and the present situation. The boy pauses, looks about, and sees on the bank a pole and several large stones. He has walked on poles and on fences, he therefore sees himself putting the pole across the stream and walking on it. This may be in actual visual imagery, or it may be in words. He may merely say, "I will put the pole across and walk on it." But, before having time to do it, he may recall walking on poles that turned. He is not then satisfied with the pole idea. The perception of stones may next become clear in his mind, and if no inhibiting or hindering idea comes up, the stone idea carries him into action. He piles the stones into the stream and walks across. As was mentioned above, the flow of ideas may take different forms. The imagery may take any form but is usually visual, auditory, motor, or verbal. Further discussion of the point that reasoning is determined by past experience may be necessary. Suppose the teacher ask the class a number of different questions, moral, religious, political. Many different answers to the questions will be received, in some cases as many answers to the questions as there are pupils. Ask whether it is ever right to steal, whether it is ever right to lie, whether it is ever right to fight, whether it is ever right to disobey a parent or teacher, whether oak is stronger than maple, whether iron expands more when heated than does copper, whether one should always feed beggars, etc. The answers received, in each case, depend on the previous experience of the pupils. The more nearly alike the experiences of the pupils, the more nearly alike will be the answers. The more divergent the experiences, the more different will be the answers. The basis of reasoning is ultimately the same sort of thing as the basis of habit. We have repeated experiences of the same kind. The ideas of these experiences become welded together in a definite way. Association between certain groups of ideas becomes well fixed. Later situations involving these groups of ideas set up definite trains of association. We come always to definite conclusions from the same situations provided that we are in the same mental set and the factors involved are the same.