In short, power to concentrate attention means power in all the mental processes. EXERCISES Exercise I. "Watch a small dot so far away that it can just be seen. Can you see it all the time? How many times a minute does it come and go?" Make what inference you can from this regarding the fluctuation of attention during study. Exercise 2. What concrete steps will you take in order to accommodate your study to the fluctuations of attention? Exercise 3. The next time you have a lapse of attention during study, retrace your steps of thought, write down the ideas from the last one in your mind to the one which started the digression. Represent the digression graphically if you can. Exercise 4. Make a list of the things that most persistently distract your attention during study. What specific steps will you take to eliminate them; to ignore the unavoidable ones? CHAPTER IX HOW WE REASON If you were asked to describe the most embarrassing of your class-room experiences, you would probably cite the occasions when the instructor asks you a series of questions demanding close reasoning. As he pins you down to statement of facts and forces you to draw valid conclusions, you feel in a most perplexed frame of mind. Either you find yourself unable to give reasons, or you entangle yourself in contradictions. In short, you flounder about helplessly and feel as though the bottom of your ship of knowledge has dropped out. And when the ordeal is over and you have made a miserable botch of a recitation which you thought you had been perfectly prepared for, you complain that "if the instructor had followed the book," or "if he had asked straight questions," you would have answered every one perfectly, having memorized the lesson "word for word." This complaint, so often voiced by students, reveals the fundamental characteristic which distinguishes the mental operation of reasoning from the others we have studied. In reasoning we face a new kind of situation presenting difficulties not encountered in the simpler processes of sensation, memory, and imagery, and when we attempt to substitute these simple processes for reasoning, we fail miserably, for the two kinds of processes are essentially different, and cannot be substituted one for the other.