The same law is illustrated by a familiar catch. Ask a friend to define the word "spiral." He will find it difficult to express the meaning in words. And nine persons out of ten while groping for appropriate words will unconsciously describe a spiral in the air with the forefinger.
Swing a locket in front of you, holding the end of the chain with both hands. You will soon see that it will swing in harmony with your thoughts. If you think of a circle, it will swing around in a circle. If you think of the movement of a pendulum, the locket will swing back and forth.
These experiments not only illustrate the impelling energy of thought and its power to induce bodily action, but they indicate also that the bodily effects of mental action are not limited to bodily movements that are conscious and voluntary.
The fact is, every mental state whether you consider it as involving an act of the will or not, is followed some kind of bodily effect, and every bodily action is preceded by some distinct kind of mental activity. From the practical science point of view every thought causes its particular bodily effects.
This is true of simple sensations. It is true of impulses, ideas and emotions. It is true of pleasures and pains. It is true of conscious mental activity. It is true of unconscious mental activity. It is true of the whole range of mental life.
Since the mental conditions that produce bodily effects are not limited to those mental conditions in which there is a conscious exercise of the will, it follows that the bodily effects produced by mental action are not limited to movements of what are known as the voluntary muscles.
On the contrary, they include changes and movements in all of the so-called involuntary muscles, and in every kind of bodily structure. They include changes and movements in every part of the physical organism, from changes in the action of heart, lungs, stomach, liver and other viscera, to changes in the secretions of glands and in the caliber of the tiniest blood-vessels. A few instances such as are familiar to the introspective experience of everyone will illustrate the scope of the mind's control over the body.