²In the case where you have no particular task to perform, the spontaneously appearing thoughts may not be properly called “wandering”, but, for example, “spontaneous”. Some authors strictly reserve the word “wandering” for the case where the thoughts are intrusive in the sense of occurring against your will while you are trying to concentrate on some task, such as thinking about some unrelated event tomorrow when trying to concentrate on reading a textbook. In this book, I use the term wandering thoughts a bit more liberally, sometimes including thinking that jumps from one topic to another when there is no particular task on which it is supposed to concentrate—as in lying on the sofa after work—since in real life, it is often difficult to draw the line between wandering and other spontaneous thinking.