When the wind blew over the stone egg, out emerged a monkey made of stone that could already walk and crawl. As the monkey looked around, beams of light shot out from his eyes toward the Jade Palace (天宫 Tiān gōng) in heaven and must have caused a fuss because the Jade Emporer (玉帝 Yù dì) ordered soldiers to investigate the mysterious blast of light.
The soldiers returned and reported that as the monkey ate and grew, the light began to die out. The Jade Emporer then made possibly the worst decision of his career - he dismissed the monkey as insignificant and carried on with his heavenly day to day activities.
The monkey began exploring the mountain and quickly found other monkey friends to play with. They would play in the river and eat from the bountiful fruit trees, life was good. But young minds are curious, and one day the monkeys decided to venture up the mountain in an attempt to locate the source of the river.
Soon the monkeys came across a waterfall and decided that whichever monkey got through the waterfall, located the source and returned would be declared their king. The soon-to-be Monkey King immediately volunteered, leapt through the waterfall and located what is now known as Water Curtain Cave (水帘洞 Shuǐ lián dòng). He emerged and beckoned the rest of the monkeys to follow him through. One-by-one they made their way through the waterfall and into what would be their new home.
Of course, the Monkey King then held them to their word and is declared king of the monkeys. He then gave himself the first of many titles, "Handsome Monkey King" (美猴王 Měi hóu wáng).
It is here in Water Curtain Cave that the monkeys lived happily and prospered for hundreds of years under the rule of the Monkey King. But as time went by, the Monkey King became more and more aware of his mortality and finally decided to take matters in to his own hands.
The Monkey King's Journey for Immortality
On his 400th birthday, after being told by one of his subjects that there were things in this world that are greater than kings, such as immortals (神仙 Shén xiān) and Gods (神 Shén), the Monkey King decided he too wanted these titles, and set off across the Great Sea the very next day in search of an immortal in the hope that they could teach him the way.
After years of searching he was pointed towards a place called the Mountain of Heart and Mind (灵台方寸山 líng tái fāng cùn shān) where he found the Cave of the Slanting Moon and Three Stars (斜月三星洞 xié yuè sān xīng dòng). It was here that he finally met his master, Puti (菩提祖师 Pú tí zǔ shī), the immortal sage, who agreed to take him on and immediately names him Sun Wu Kong (孙悟空 sūn wù kōng).
What's in a Name?
Familiy Name 孙 Sūn
You see, up until this point, having been born without a mother or father from a rock atop the Mountain of Flowers and Fruit, the Monkey King didn't actually have a name. Master Puti observed that the Monkey King resembled a macaque monkey, which in Chinese is written 猢狲 Húsūn. The second character 狲 is the same as 孙 if you delete the radical on the left 犭which denotes that the character is related to an animal. 孙 is also a very masculine character, connected to sons and grandsons. And 孙 is quite a common family name in China, so it fit perfectly.
Here are some other animal related characters, note that each has the same radical on the left 犭 : 狗 dog, 猫 cat, 猪 pig, 狼 wolf.
The reason Master Puti didn't select 猢 Hú is because the character 胡 Hú (without the 犭radical) - which is also a Chinese family name - is a very feminine character, and is associated with the menopause. If the Monkey King were a Monkey Queen, perhaps she would be called 胡悟空 Húwùkōng...who knows?
As for 悟 wù and 空 kōng, well these are a little more difficult to explain. But let's have a stab at in it.
Second Character 悟 wù
So similar to how western families carry on names through the generations ("Junior" or with numbers, like “”King Henry VIII,“” for example) Chinese families used to have a system for the second character in a persons name. In the example of the Monkey King, he arrived at the Cave of the Slanting Moon and Three Stars (斜月三星洞 xié yuè sānxīng dòng) when Master Puti was using 悟 wù. He seemed to have a system of 12 characters he used and just so happened to be on 悟 wù at the time. Those 12 characters were:
广 大 智 慧 真 如 性 海 颖 悟 圆 觉 (Guǎng Dà Zhì Huì Zhēnr Rú Xìng Hǎi Yǐng Wù Yuán Jué)
Third Character 空 kōng
In accordance with the concept of the Five Phases (五行之气 wǔ xíng zhī qì), Master Puti realised that the Monkey King was overly interested in material things. In Buddhism, the material realm is considered to be a distraction from what is truly important, namely, the spirit world, which is why material things are referred to as 空 (kōng) or 虚空 (xū kōng) - which translated literally means 'empty' or 'void.'
This third character therefore represents the Monkey King himself, and is used as a way of guiding him to a higher state of mind. A wish bestowed upon him by his Master.