When I was first learning Tai Chi, the word "transition" was used often. Holding the Ball was a transition into Part the Wild Horse's Mane. Circling the arms was a transition for Brush Knee Step Forward. After changing teachers and styles, I learned a simple truth:
There are no transitions in Tai Chi.
As I later learned, a self-defense application is built into every movement in Tai Chi. Every movement.
No matter where your hands and feet are, a fighting application is there.
Here is a case in point, one of 108 self-defense applications demonstrated through 259 photos in my new ebook, Yang Tai Chi 24 Form Self Defense. The ebook is only $4.99 through Amazon Kindle -- a great reference for those who practice Yang style Tai Chi, particularly the 24 Form.
Let's say that someone comes up behind you and grabs your shoulder, preparing to punch your lights out. Now, this could even be done from a clinch position or against a punch, but I'm showing this particular set-up as a way to demonstrate the movement.
In picture 2, you step in and your arms have circled as they would in the "transition" before the hand moves out in Brush Knee.
Notice that you have used your leg to block his, setting up some pretty good leverage. Your arm is under his armpit.
Tai Chi is a closeup fighting art, designed to break an opponent and put them on the ground. It is a martial art. Every movement is a hidden or obvious martial arts technique.
If you are only practicing for health and meditation, you are not practicing a complete art. When you understand what the movements are designed to accomplish -- yes, the "intent" (which is NOT to cultivate chi) -- you will further understand how the body is supposed to move, and the "energy" you are supposed to feel.