Impulse is a form of cerebral activity which, forces us to make a movement before the mind is able to decide upon it by means of reflection or reasoning. The Shogun deals with it at length and defines it thus:
"Impulse is an almost direct contact between perception and result.
"Memory, thought, deduction, and, above all, reason are absolutely excluded from these acts, which are never inspired by intellectuality.
"The impression received by the brain is immediately transmuted into an act, similar to those acts which depend entirely on automatic memory.
"It is certain in making a series of movements, which compose the act of walking upstairs or the action of walking from one place to another, we do not think of analyzing our efforts and this act of walking almost limits itself to an organic function, so little does thought enter into its composition.
"In the case of repeated impulses, it can be absolutely affirmed that substance is the antecedent and postulate of the essence of being.
"Substance comprises all corporal materialities: instinctive needs, irrational movements, in a word, all actions where common sense is not a factor.
"Essence is that imponderable part of being which includes the soul, the mind, the intelligence, in fact the entire mentality.
"It is this last element of our being which poetizes our thoughts, classifies them, and leads us to common sense, by means of reasoning and judgment.
"He who, having received an injury from his superior, replies to it at once by corresponding affront, is absolutely sure to become the victim of his impulses.