Apart from the Instincts, the principle holds that behind every action which our conduct shows there must be something thought of, some sensation or knowledge then in mind, some feeling swelling within our breast, which prompts to the action.
This general principle is Motor Suggestion.

It simply means that we are unable to have any thought or feeling whatever, whether it comes from the senses, from memory, from the words, conduct, or command of others, which does not have a direct influence upon our conduct.

We are quite unable to avoid the influence of our own thoughts upon our conduct, and often the most trivial occurrences of our daily lives act as suggestions to deeds of very great importance to ourselves and others.

For example, the influence of the newspaper reports of crime stimulate other individuals to perform the same crimes by this principle of suggestion; for the fact is that the reading of the report causes us to entertain the thoughts, and these thoughts tend to arouse in us their corresponding trains of suggested action.
The most interesting and striking sphere of operation of the principle of Suggestion (of other sorts as well as motor) is what is commonly known simply as Hypnotism.

To that, as well as to further illustrations of Suggestion, we will return later on.
We are able, however, to see a little more in detail how the law of Motor Suggestion works by asking what sort of action is prompted in each case of thought or feeling, at the different levels of the mind's activity which have been distinguished above as all illustrating Apperception--e.g., the stages known as Perception, Imagination, Reasoning, etc.
We act, of course, on our perceptions constantly; most of our routine life is made up of such action on the perceptions of objects which lie about us.