Ken Fish recently opened thread "what internal means, IMO". Perhaps it will be interesting to someone to read a few random thoughts about this subject from my point of view:
In the very beginnings of Chinese writing system, character wu 武 of wushu 武術 was equal to character wu 舞 meaning dancing and also to character wu 巫 meaning witchcraft (all three characters were more-less interchangeable). And the whole Chinese culture is originally of Daoist (understand shamanic) origin. Daoism is usually divided into Daoist philosophy (Daojia) and Daoist religion (Daojiao), although many scholars recently expressed their doubts about meaningfulness of this distinction. And surely, men like Laozi or Zhuangzi were not only philosophers - because no philosopher can discover that "normal people breathe from throat, wise men breathe from heel" (Zhuangzi chapter 15), this is expression of practical knowledge of the body practice, of inward training, and man with this kind of knowledge is not "philosopher" anymore, he is simply practitioner. If there is any difference between Daojia and Daojiao, it is that former were satisfied with "life and death cycle" while latter tried to reach physical immortality by various spiritual techniques, primarily by sex, breathing, massages, movements of the body, physiological alchemy and meditations - but many of these spiritual techniques were practiced by both groups.
Therefore there are breathing and other techniques described in Guanzi (text whose some parts are supposed to be even older than Laozi, including chapter with breathing, called Neiye, Inward Training), there is Laozi, Zhuangzi and other "philosophers" with many descriptions of various spiritual techniques, there are numerous texts belonging to Daoist "religion", there are many "professional" text (like text of medicine, astrology, sexual education etc.) and the same thing is even in the chan/zen Buddhist scriptures - through all of them you can see the same thing in the background: returning jing into qi and shen, returning jing to nourish brain.
And you can find the same thing related to all great internal martial artists: it is said about Chen Wanting (ancestor of Chen style taijiquan) that he always had Huang ting scripture with himself and this very important book of internal alchemy, founder of baguaquan Dong Haichuan taught system that is obviously related to very deep level of alchemy, Sun Lutang wrote directly about special system of microcosmic orbits (different from the general view of Chinese medicine), Sun Xikun (of baguaquan) wrote about general principles of alchemy, Du Xinwu (of Ziranmen) was direct inheritor of one of the nei-dan (inner elixir) school, as well as recently departed Wang Yannian (of taijiquan)...
TCMA is truly a child of this system of Chinese physiological alchemy. Of course, no system can exist in its pure form and therefore TCMA was mixed with medical practitioners, with street performers, with professional fighters (bodyguards as well as criminals). The aim of alchemy is to know myself, if I know myself, I know also others and naturally physical knowledge means knowledge of using the body in various circumstances, including fighting. This is the way from top to the bottom, I would say. But there was always way from the bottom to the top: many fighters later became practitioners - for example, the most frequent reason for stopping to practice martial arts in Taiwan is that practitioner becomes fully involved in some religion... If you know alchemy or religion or any higher knowledge, you will not have interest in fighting - and that is also reason why there are not so many internal TCMA figters: to them, fighting is for laugh - they can fight but they are not interested to fight. Interest in fighting is low-level, it just shows that person does not know too much...
Kungfu and traditional Chinese martial arts is direct descendant of this search for physical immortality. TCMA is follower of those Daoist practices and Shamanic techniques working with one's own self. It is centered inward, not outward.
Oldest xingyi is just combination of wuxing (five phases or elements) and animal styles, later taijiquan is based on liangyi (yin-yang) theory (including five phases, imho) and latest baguaquan combined all those principles of liangyi, wuxing and bagua. In the terms of internal - external dichotomy, besides excellent article of Zhang Yun (
http://www.ycgf.org/Articles/Neijia-Waijia/arti_NW.htm) there are also other characteristics:
1. focus: mind of external artist is on the result (process is less important) - mind of internal artist is on the process (result is less important)
Your result: if your aim is fighting, you are external, you can not be internal because if your mind is outside, on your opponent, you can not be aware of details inside of your body (which means that 99% of people who proclaim to be internal do not know what they are talking and they are not internal at all).
2. zangfu: internal artist works directly with internal organs, especially five zang/full organs heart, lungs, liver, kidney and spleen - external artist does not.
Your result: if you do not feel or even do not know where your spleen actually is and how it works, stop dreaming about being internal.
3. system: xingyi is wuxing system, taiji is liangyi system, bagua is bagua system, for internal artist, these three systems should become his/her own body (or in his own body, if you prefer this formulation) and those systems are "working organs" of his art - naturally external artist does not have this thing.
Your result: if you do not feel wuxing, taiji and bagua inside of your body, if they are not part of your body, then why to call it internal?
4. alchemy: internal artist works jing - qi - shen - void transmutation and this necessarily means also a change of character - external artist does not have chance to understand it practically and if he changed his character, it is not direct consequence of this transmutation.
Your result: if you did not change during your practice, if you are still this self-centered fighter, you did not understand anything, you failed.
Regards
Miro
We have entered a voyeuristic, or "phanic," era where esoteric ideas and methods are only unveiled and put within reach of everyone because they no longer have any chance of being understood. (Mircea Eliade)