Here's a little story for you.

A man goes into a nightclub with his younger wife. After a few hours drinking, he decides that the twenty-something Hispanic man sitting opposite them is staring at his pretty wife a little too hard. After a few more drinks, he decides to take exception to this, and confronts this Hispanic man, spitting in his face as he screams insults at him, seemingly uncontrollably. After having his say, he sits down again, satisfied.

About forty minutes later, he leaves the club and is attacked and stabbed by the Hispanic man and his older brother, who was also there that night. He survived the attack—just—but now will require a catheter for the rest of his life, due to his wounds.

This is not a made-up story; it happened just two nights ago in a club near my building, and is now splashed over page four of the local newspaper. I bet you could tell me similar stories yourself. They are all too common.

Many martial arts claim "spiritual" roots, but very often modern exponents have trouble explaining what these roots are. But here, you can see the origins. Psychic development—including the eradication of negative, "unspiritual" emotions—is essential in developing becoming a superior warrior. Our psychological vices slow us down. They make us weak. The best disposition is one of cool rationality; the further you depart from this calm, collected (yet alert) mental state the weaker you become.

You see this in the news story I've just related. The husband's anger blinded him to the dangers around him—namely the presence of the brother of the man he was screaming at. He could have walked away early on, but his vanity forced him to take his "enemy" to task. He could have gained his revenge at a more appropriate time, but he was too lazy to wrestle with his own dumb impulses. And if he had really needed to act, he should have done so, rather than shouting and making a spectacle of himself. But he held back. He was afraid to launch an immediate attack (which wouldn't have been legitimate anyway).

Ninjutsu philosophy takes this basic idea of warrior-weakness further. In accord with their Shinto theory of the five elements, they saw five psychic weaknesses to which every man (and woman) is heir. They are:

• ANGER
• VANITY
• LAZINESS
• FEAR
• SYMPATHY

To this, I would add a sixth weakness: GREED. The type of greed that renders the body fat and feeble, or encourages the misuse of substances like alcohol or recreational drugs—which simply retard reasoning and decision-making capacities and throw the perceptual skills out of whack.