We are brought back again, then, to the necessity of occasionally thinking in silence. There is one other reason why we shall sometimes need to do this. Thoughts of certain kinds are so elusive that to attempt to articulate them is to scare them away, as a fish is scared by the slightest ripple. When these thoughts are in embryo, even the infinitesimal attention required for talking cannot be spared. But later, as they take more definite and coherent form, they can and should be put into words, for otherwise they will be incommunicable and useless. No definite rule can be laid down, however, as to what should be spoken and what thought of silently. This depends to a large extent upon the individual thinker. Some will probably find that talking helps them in almost all their thinking, others that it is often an actual hindrance. The same is true of closing one’s eyes. If you do not know which is better for you, find out by experiment. At those times when you suddenly catch yourself wandering, it would be a good plan to stop occasionally and trace back your train of thought to the point where it left its original direction. In this way you would get some valuable insight into the _how_ and _why_ of mind wandering; you would be helped in recognizing its appearance sooner the next time it occurred. Whenever a person is left alone for a short time, with no one to talk to and no “reading matter”; when for instance, he is standing at a station waiting for his train, or sitting at a restaurant table waiting for his order, or hanging on a subway strap when he has forgotten to buy a newspaper, his “thoughts” tend to run along the tracks they have habitually taken. If a young man usually allows a popular tune to float through his head, that will be most likely to happen; if he usually thinks of that young lady, he will most likely think of her then; if he has often imagined himself as some great political orator making a speech amid the plaudits of the multitude, he is likely to see a mental picture of himself swinging his arms, waving flags and gulping water.