The Words of Jou Tsung Hwa

The late Tai Chi Master Jou Tsung Hwa wrote the absolute best book on Tai Chi Chuan I have ever read. In his book "The Tao of Tai Chi Chuan; The way to Rejuvenation", Master Jou writes:

"Finally, when one has acquired Ching, or lightness, Man, or slowness, Yuan, or complete circularity of motion, and Yun, or constant rate, one will have completed the human stage. How can one verify this accomplishment? One will have followed the rules in the human stage when the practice of Tai Chi Chuan outdoors does not disturb flocks of birds or other animals".

Master Jou is discussing the various stages of mastering Tai Chi Chuan, the "human" stage being the first.
This notion is something that makes Tai Chi Chuan so much different than hard-style martial arts. Jou suggests a learning curve that mimics and strives to actually become part of the natural world.

It's almost embarrassing to relate this story, but it fits the topic. Years ago I had to fill in and help out at a dog kennel. It was at a time when I was really, really trying hard to prepare for a Tae Kwon Do belt test. While I was doing my chores at the kennel, I absent-mindedly slipped into a few movements of a form; block, punch etc.
Well, as expected, the animals in the kennel did not like it at all, and when they became frightened, I stopped my movement immediately.

This is what Jou is talking about. Not only was my martial movement snappy and aggressive, I was nowhere near the enlightened stage Jou claims to seek.

Lightness, slowness, circularity of motion, and constant rate is what makes Tai Chi Chuan a martial art of the natural world.