The kindness overcomes the brute strength, what is formless cannot be stopped.
Defeat 1000 pounds using 4 ounces, this is the Way of Taijiquan, Yin and Yang. Where the opponent is strong (yang), the practitioner of Taiji is not there, like a ghost, where the enemy is weak (yin) the practitioner of Taiji drives his strength, like a river in flood. The adversary can not find any resistance to apply its apparent strength, falling out from its center and discovering its real weakness. Free from superficial mind that imprisons him and makes him clumsy the practitioner of Taiji becomes formless water, he flows away without resistance and penetrates deeply, creating a strong vortex as a center: unstoppable but constantly adapting he thus manifests his True Strength.
Relying blindly on the external forces leads to uncertain results in fighting and to certain failure in life and beyond.