Stages of Taiji - Big Strong Fast Light

The book "Flashing Steel" talks about four stages in training, namely "big, strong, fast, light". How does this apply to taiji?

Big: This is the stage in which we are concerned only with the big (aka main, broad) movements. We have yet to start paying attention to details, and we are performing our movements big and broad. We adopt lower stances to build up our leg muscles. This is usually what people call the "big form". The aim of this stage is to know the movements, and build up a good foundation.

Strong: This stage is when we have built up a proper foundation, when we are able to properly transfer the force from our legs to our arms. We are able to apply force without brute muscular strength, with the force being generated from our legs. The aim of this stage is to be able to properly manifest the strength generated by our legs to where we need that force.

Fast: In this stage, we are now longer constrained by the slow movements of taiji, being able to adapt our rhythm to suit the opponent. While in previous stages, moving fast meant using muscular strength, in this stage, we are able to move our bodies as a whole, and can move fast without having to resort to muscular strength. The aim of this stage is to be able to properly manifest the spirit of "fast forms" without having to resort to brute strength.

Light: This is the stage in which, having mastered the fundamentals of taiji, we are able to move our bodies as a whole, to adapt ourselves to suit the rhythm of our opponents, such that we can move fast or slow. The aim of this stage is to be able to move light as a feather such that our opponent cannot figure out where our force is coming from, yet because we are so light, we can react even faster to any changes.