Spirit of Jūdō: The Principle of Jū

"True spirit of Judo is nothing but the gentle and diligent free spirit. Judo rests on flexible action of mind and body. The word flexible however never means weakness but something more like adaptability and openmindedness. Gentleness always overcomes strength." Kyuzo Mifune^[7]

The principle of Ju (柔 Jū, Yawara^?) underlies all classical Bujutsu methods and was adopted by the developers of the Budō disciplines.

Acting according to the principle of Jū, the classical warrior could intercept and momentarily control his enemy's blade when attacked, then, in a flash, could counter-attack with a force powerful enough to cleave armor and kill the foe.

The same principle of Jū permitted an unarmed exponent to unbalance and hurl his foe to the ground. Terms like "Jūjutsu" and "Yawara" made the principle of Jū the all-pervading one in methods cataloged under these terms. That principle was rooted in the concept of pliancy or flexibility, as understood in both a mental and a physical context. To apply the principle of Jū, the exponent had to be both mentally and physically capable of adapting himself to whatever situation his adversary might impose on him.
 
There are two aspects of the principle of Jū that are in constant operation, both interchangeable and inseparable.

One aspect is that of "yielding", and is manifest in the exponent's actions that accept the enemy's force of attack, rather than oppose him by meeting his force directly with an equal or greater force, when it is advantageous to do so. It is economical in terms of energy to accept the foe's force by intercepting and warding it off without directly opposing it; but the tactic by which the force of the foe is dissipated may be as forcefully made as was the foe's original action.

The principle of Jū is incomplete at this point because yielding is essentially only a neutralization of the enemy's force.

While giving way to the enemy's force of attack there must instantly be applied an action that takes advantage of the enemy, now occupied with his attack, in the form of a counterattack. This second aspect of the principle of Jū makes allowance for situations in which yielding is impossible because it would lead to disaster. In such cases "resistance" is justified. But such opposition to the enemy's actions is only momentary and is quickly followed by an action based on the first aspect of Jū, that of yielding.

Budō (武道^?) is a Japanese term describing martial ways.^[1][2][3] Literally translated it means the Way of War. In modern usage, bujutsu, meaning martial/military art/science, is typified by its practical application of technique to real-world or battlefield situations. Budō, meaning martial Way, has a more philosophical emphasis. The "dō" is a reference to this path.^[11]