Allow: this is the yin practice of acceptance – allowing things to be as they are in this moment. In our Western culture, the drive is to change the world. At a very early age we are exhorted to be active, to do something, to make something of ourselves. We are told to go out and change the world. This is the essence of yang – all our heroes and role models are yangsters.
And there is nothing wrong with being a yangster! There are certainly times in life when the most appropriate thing to do is to take action. As we already discussed, if we see a child being beaten, we take action to change that. But if we are constantly in yang mode, we will soon burn out. Stress without rest is not balanced living. We need, at times, to just let the world be the way it is.
In reality there are actually very few times we can change the world or change the situation we are in. Our ego would like to believe we can always do something, but this is simply not true. There are many times when the appropriate action is inaction, because there is nothing we can do, except perhaps make things worse.
Allowing things to be as they are is an important skill to learn. This is not one that is prized or taught in our culture. Maybe for one or two weeks of the year, we are told to take a vacation, to take a break and rest. But then we fill those two weeks with all sorts of yang activities, and we get no closer to really balancing our inner and outer worlds. Two weeks, of course, is hardly enough to balance fifty weeks of feverish living. We need to learn to allow every day. Practicing Yin Yoga is an excellent time to learn to allow, to accept, what is happening without reacting or trying to change the world.
King Canute was famous for trying to change the world. He tried to stop the tide from coming in. He failed, of course, and as a consequence got all wet. 
Practice allowing; begin with your breath allow it to be whatever it wants to be. This is not easy! Once our ego becomes aware of the breath it thinks it can do a better job and tries to control it. But practice allow the breath to just be.
When a fear sneaks upon you allow it in! Welcome it, as King Canute welcomed the water. The ego is the attendant flattering you with false praise. Ego is whispering in your ear, “Push the fear down! Keep it hidden just command it and it will go away!” Show the ego that you don’t have to fight the fear. Resisting fear is fruitless – let it come, just as we allow the waves to come ashore. 
When we learn to allow what is happening we take power away from whatever is happening. This is a principle of martial arts practice: do not resist. When we resist what is happening, we weaken ourselves and give power to that which we resist, making it stronger. According to Jung, “What we resist, persists.” Instead practice allowing.
- — By the way, the mythical king knew what he was doing. He was proving a point to his flatterers and attendants. They were the ones saying that he was so great and powerful that he could command the very oceans of the world. To teach them a lesson he ordered his chair to be placed in the path of the oncoming waters. The rest is mythic history.
- — Jung noticed that there exists a frightening part of our psyche that he called “the shadow.” The shadow is formed by resistance: everything that we deny about ourselves we throw into a dark bag we carry behind us. But what we resist doesn’t go away or become weaker: it hides and grows stronger. The shadow is very scary. We will do anything to avoid facing it; including projecting its attributes onto others and blaming them for the very weaknesses we deny exist in ourselves. It is unfortunate when a person projects his shadow onto another person. It is catastrophic when a country projects its shadow onto another country: war is often the result. This is the price of not allowing.