Tai chi teaches us to move with structure, balance and flow.
Structure is alignment of the joints that takes forces into the bones, giving muscles mechanical advantage.
Balance is alignment with gravity that provides central equilibrium, keeping the body planted and upright.
Flow is complimentary muscular activation, allowing us to move without stress by literally getting out of our own way.
The combination of structure, balance, and flow gives rise to effortless power; deficiency in any one gives rise to powerless effort.