During the period studied by the politician, human nature has changed very little, but political environment has changed with ever-increasing rapidity.
Those facts of our environment which stimulate impulse and action reach us through our senses, and are selected from the mass of our sensations and memories by our instinctive or acquired knowledge of their significance.

In politics the things recognised are, for the most part, made by man himself, and our knowledge of their significance is not instinctive but acquired.
Recognition tends to attach itself to symbols, which take the place of more complex sensations and memories.

Some of the most difficult problems in politics result from the relation between the conscious use in reasoning of the symbols called words, and their more or less automatic and unconscious effect in stimulating emotion and action.

A political symbol whose significance has once been established by association, may go through a psychological development of its own, apart from the history of the facts which were originally symbolised by it.

This may be seen in the case of the names and emblems of nations and parties; and still more clearly in the history of those commercial entities--'teas' or 'soaps'-- which are already made current by advertisement before any objects to be symbolised by them have been made or chosen.