The unspoken secret within the Yin Yang duality
If you wrote down a word and circled it with a closed circle, you've just created duality.
If you wrote "man," in the circle, you created "woman," outside. If you wrote "hot," you created "cold," outside. BMW? Mercedes Benz. Nike? Addidas. Truth? Falsehood. Day? Night.
Everything you create creates an opposite. This is the law of the yin yang. The moment you say something is something, you've also created it's opposite.

How does this apply to your life?
"My boyfriend/girlfriend is my soulmate!" Creates the only person who will break your heart.
"I hate my job!" Creates a love for somebody else's job. Making you even more miserable.
"I am such an idiot!" Creates a world of idiots around you. Do you want to be surrounded by idiots outside of your inner circle?
This is what is meant when people say, "it is what it is." They don't realize that they mean to leave an event, thought, person, action, just as it is so that they don't immediately create it's opposite.
Harvard Business School teaches never to celebrate a corporate success until after the success is over. Because when you circle the word "success," you've already created the vast space all around it called "failure."
This is zen. This is wisdom.
Now, you remember that taoist quote from the last page? The moment you create a yinyang taichi like the one above, you've just instantly created three from two because there is an outside. See how complicated your life is now becoming?

There was a farmer in a mountainous village in a time of superstition and fear. When the harvest came, the farmer's only horse ran off into the mountains. The villagers said, "How unlucky. The farmer only has one son and his horse just ran away. He must be cursed by the gods. He must have bad karma."
The farmer said to his son, "Good luck, bad luck, I don't know."
Three days later, the one mare that ran into the hills brought back three stallions. The villagers fearing the bad karma they circled around the farmer recanted saying, "See? What an outstanding citizen. The god's have blessed him. He is lucky."
The farmer said to his son, "Good luck, bad luck, I don't know."
The next day, while the son was getting ready to yoke ("yoga" in sanscrit) the horses together, one reared up and kicking, broke the only son's leg. The villagers feeling vindicated started joking to each other, "We never should have second guessed our wisdom. That farmer is cursed with bad luck. We were always suspicious of him."
The farmer said to his son, "Good luck, bad luck, I don't know."
The next day, the emperor sent his army through the farmer's mountainous village and drafted, force conscripted all of the able bodied men. The farmer's son was the only man who didn't die in a far away war in a far away land.
The farmer looking at the long life ahead of his son looked into his eyes and said, "Good luck, bad luck, I don't know."
"Stop judging. For the measure you measure, it will be measured unto you." - A Jewish Alchemist
This is wisdom. This is zen.
There is much more to the number two than I want to explain here. For example, If you wrote the word "gravity," the outside of that circle would be "repulsion." If the earth has an obvious and common pulling power, It must also have a subtle and uncommon pushing power. This is the power that ancient martial artists have cultivated and mastered.
Now, do you want to learn about the number three?