Let us consider various characteristics of voluntary and involuntary acts. In the case of lifting the heavy weight, the various experiences of effort are obviously most characteristic for lifting the weight voluntarily. On the other hand, compare with this the case of writing, voluntarily, here in most of the ordinary cases there will be no effort; and even if we feel that the writing tires our hands and strains their muscles, this is not the experience of “pulling” and “pushing” which we would call typical voluntary actions. Further compare the lifting of your hand when you lift a weight with lifting your hand when, e.g., you point to some object above you. This will certainly be regarded as a voluntary act, though the element of effort will most likely be entirely absent; in fact this raising of the arm to point at an object is very much like raising the eye to look at it, and here we can hardly conceive of an effort. ‒ ‒ Now let us describe an act of involuntary raising your arm. There is the case of our experiment, and this was characterized by the utter absence of muscular strain and also by our observant attitude towards the lifting of the arm. But we have just seen a case in which muscular strain was absent, and there are cases in which we should call an action voluntary although we take an observant attitude towards it. But in a large class of cases it is the peculiar impossibility of taking an observant attitude towards a certain action which characterizes it as a voluntary one: Try, e.g., to observe your hand rising when you voluntarily raise it. Of course you see it rising as you do, say, in the experiment; but you can't somehow follow it in the same way with your eye. This might get clearer if you compare two different cases of following lines on a piece of paper with your eye; A) some irregular line like this: , B) a written sentence. You will find that in A) the eye, as it were, alternately slips and gets stuck, whereas in reading a sentence it glides along smoothly.