When you first learn form and begin exploring self defence, your attention is upon the science.
You need to align the body just-so and respond very sensitively to contact.
This process is quite difficult and you are inclined to think a lot.

The drawback is that this prevents you from truly letting-go.
It is a necessary set-back designed to help you to move in the correct manner even though you cannot feel what the right way is just yet.

If taoism is the art of adjusting to life, then tai chi is the art of adjusting to the opponent.
This process of adjustment is what yielding is about.
Balancing, sensitivity, change.

Lao Tzu, Chuang Tzu and others wrote about tao.
They observed the natural world and realised that there were distinct patterns and rules in operation.
These natural laws were too subtle to be rendered verbally, you had to intuit the way/how of them.

They realised that if you could sense the way of nature, you could move with it, rather than against it.
This offered the key principle of tai chi: yielding.

Western physics tries to understand the world through mathematics and measurement.

The ancient taoist scholars did not.
Rather than simply use the logical, rational, problem-solving aspect of consciousness, they sought to get a feel of reality.
They wanted to explore reality, not document it. 

Taoism is essentially hands-on ancient Chinese physics.

The tao cannot be defined verbally or conceived intellectually.
When you begin to understand tai chi, you have a vague sense of the system but could never express yourself coherently.
This is your first inkling of tao.

Historically a Master Craftsman or Master Tradesman would proceed through a 3-stage career path:

1. Apprentice
2. Journeyman
3. Master

This intensive approach to learning is tried and tested.
It has been the source of inspiration in modern times for changes in the UK education system.
Sometimes the old ways are better.
There are lessons in the past.