The cultivation of internal strength had always emphasised the complement of the yin and the yang, regardless of whether it was for strengthening the body and healing illnesses, or setting a foundation prior to the learning of top-notch martial arts techniques. Fire and water -- in an allusion to two things that are diametrically opposed to each other -- had to work hand-in-hand with each other, so after learning the 'Foot Shaoyin Channel of the Kidney', the 'Foot Shaoyang Channel of the Gall Bladder' should be learnt next. When the Shaoyin and the Shaoyang were blended in harmony, the strength of the body would increase.
However, Xie Yanke had told him to practise only the channels of Shaoyin, Jueyin, Taiyin, Yinwei and Yinjiao, without teaching him any of the complementary channels of Shaoyang, Yangming and the others. Consequently, the yin energy in the boy's body increased immensely over the years, while his yang energy declined. In fact, the accummulated yin energy had reached such dangerous levels that the slightest misstep would immediately be fatal.
Yet, although Xie Yanke could see the invasion of the yin energy in his body, the boy had strangely remained very much alive. Almost at once, he understood. The boy was simple and ignorant all along, without any knowledge of the affairs around him or any thoughts that might have distracted him from his training. Hence, he had not reached the point of over-practising and infatuation with power. If it were someone else, he would have been interrupted by the unavoidable emotions and desires of life, and died a long time ago from the slightest flight of fancy that arose.
Xie Yanke thought:
This 'gouzazhong' (bastard) is now stuck on this cliff with me, and I am afraid that he has to suffer for a number of years to come. If I allow him to leave, he would probably die within days of contact with the dazzling temptations of the human world. So long as this 'gouzazhong' is alive, people can use him to threaten me, so I cannot take such a dangerous risk. After some thought, he had an idea: I will teach him the techniques associated with the 'yang' channels, without telling him how to harmonise the 'yin' and the 'yang'. When the 'yang' energy in his body has reached a certain level of accummulation, it will begin to collide with the 'yin' energy. A dragon and a tiger in battle will not stop until one of them is dead. So even if there are no distracting thoughts in his heart and mind, he would still die as a result of the disharmony of energies. Yes, this plan is wonderful indeed.
Thus, he started teaching the boy the techniques associated with the Yangjiao Channel(9). He did not follow the sequence of imparting the techniques of the Shaoyang, Yangming and Taiyang Channels first; instead, he had begun with the second most difficult Channel of Yangjiao. As for the Ren and Du Channels that allowed the connection of the yin and yang energies, he ignored them not because the boy had not attained a suitable level of internal energy, but because learning the techniques associated with them did not fit into his plan.
As for the boy, he simply practised as he had been instructed. Although progress was considerably slow, he had a naturally high level of persistence that pushed him along. More than a year later, he finally mastered the Yangjiao Channel. The channels that ensued were increasingly easier to learn.