Dark Side of the Moon

拳有勢者，所以為變化也。横斜側面，起立走伏，皆有墙戶，可以攻，故謂之勢。拳有定勢，而用時無定勢。然當其用也，變無定勢，而實不失勢，故謂之把勢*

Fists have a posture, which implies changes. Transversal, oblique, sideways or frontal, getting up, standing, moving or lying prostrate, everything has walls and doors, attack being then possible, therefore we talk about posture. Fists have fixed postures, but when boxing there is no fixed posture. So that it undertakes its own usefulness, changes knowing no determined posture and yet one actually not losing posture, which is the way to be skilful in the art.

戚繼光曰：“操手足之號令易，而操心之號令難；有形之操易，而不操之操難”**

Qiji Guang said: " The command to practice the hands and feet is easy, but the one to train the heart hard; practicing form is easy, but the drill with no drill hard"

For old internal practices, fighting was chaos, hence no rule, while training, to compensate, had to be made with method, hence rules and order. Training with rules for the chaos was another oxymoron to be solved. Indeed, because fighting was chaos, one would aim to reach the formless even though training was ruled by form. There are therefore a lot of sayings in Chinese martial arts that, as oxymorons, ask the students to do the opposite in fighting of what was done while training.
Before explaining in details a few general principles, the basic logic behind it should be understood. In internal practices, training mainly focuses on obtaining useful skills and maintain a healthy body, athletic and full of vitality, while combat is mainly a question of experience and can only be taught while doing so. Of course, there will still be bridges, it is just trends after all, not strict rules.

Training for Skills

In old internal practices, the main aim was to deeply transform the body in order to obtain skills useful for fighting, or improve existing ones, and keep the body in its utmost shape. The aim, because they considered that the best answer to chaos was to be what would be called formless, "My skills know neither form nor appearance"***, as the saying goes, was not to learn a set of techniques useful in combat but to improve one's speed, accuracy, endurance, power, flexibility, resistance, energy saving, vigilance, motor skills... or any other skill useful when fighting. That is why routines, with or without weapons, were never a set of techniques for internal practices and two people, or more, fixed scenario simulations were never practiced.

To train for skills, one still needed form, hence routines, postures, exercises... all designed to acquire or improve skills, but certainly not to study a technique. That is how being able to do the splits was not made for enabling high kicks, but for improving one's fascias elasticity, so power and speed, and organs, so vitality, all other flexibility exercises done in the same spirit. Longer routines were also made to improve one's body nimbleness, both by making it move in all kind of directions with all kind of angles and by devising ways to train the brain to decipher conflicting informations, like asymmetric movements, but certainly not a collection of fighting techniques. Two or more persons drills, also, were never simulations with a fixed scenario, but a way to improve one's vigilance, intuitive reaction and nimbleness.

Skills obtained, one could finally fight and, thus, learn how to use them.

Experience for Fighting

A known story in Chinese Martial Arts is the one of a student practicing in a mountain. Every time he thinks he is ready, he would try to leave the mountain just to be challenged by an older student. This would go on until he was able to finally raise to the challenge.

If the ancients believed that, once enough skills obtained, the best way to learn fighting was to do so, they did not want to put their students in too dangerous situations before they thought they were ready. To achieve such goal they would try to control the fighting environment, whether by fighting within the school or by making sure the opponent was of a far lesser level.

Within the School

One of the few exceptions in the world of weapons, fighting would be made empty handed, apart maybe from some extreme schools which did not really care for their students welfare, weapons being not very forgiving. People being much stronger, and elders normally able to control the amount of force of their blows, they were fights with neither rules nor protection, fighting empty handed, compared to the perils of fighting with weapons, being much easier. Because the elders could hit with enough force to make it very painful without hurting the student, it would allow very good mistakes reminders without the dire consequences. Nowadays, in peaceful societies where physical violence is nothing compared to what it used to be and with much weaker bodies less used to physical contact and pain, training has switched to what is called sparring, even light sparring, with protections. 

Once the elders could not beat the student, the fighting training within the school was considered achieved.

Outside

There, it would only be with weapons, and danger was everywhere. To achieve success, the logic of the training within the school, facing someone of higher level, would be reversed, the teacher making sure his/her student would face someone he could beat in a heartbeat. Still, because outside fighting is the realm of the unknown, the student would be watched over by elders from the school, who would make sure to intervene if things would go wrong, being a kind of safety belt. If successful, the student would, then, be confronted with people of higher levels until it was decided he/she had gained enough experience to wander in the world.

Nowadays, of course, firearms and/or local legislation don't allow such baptism by fire.

Of course, those being trends, there would be some trainings directly targeting fighting.

Where Training Meets Fighting

On one hand, because training routines and postures were evolutive in the old practices, once the necessary skills obtained, the body would naturally be transformed in a way its motion would be closer and closer to the ones needed in fighting. Indeed, the higher training of the whole body force requires very short and close moves, same requirements as those in fighting. 

On the other hand, the search of the best move adapted to one's body, one would start by training the principle of a "move for everything". Indeed, if long routines for weapons were made to train the body to move in an as nimble way as possible with the chosen weapon, students were also training the "one move", like unsheathing for the broadsword, poking for the sword, thrusting for the spear... Those imposed "one move" were a way to teach student to mainly keep only to one technique while fighting, it was up to them to find after their favourite move, the one they would use most of the time while fighting. Hence, there are numerous stories in the Chinese martial arts of people having learned and fighting with only one technique. Unicity to answer the multiplicity of changes in the chaos of fighting, another oxymoron.

Finally, breathing, because it had to become a second nature, was the thing one would keep the same whether training and fighting, deep, long and uninterrupted, never panting. Organs, mind and spirit techniques too.

In car racing, the car is as important as the driver, and improving a car does not follow the same principles as learning how to drive. It is the same logic with old practices, enhancing one's body and learning how to fight with it being actually two different things. Therefore, whatever skills one has trained are often the hidden part of an iceberg when fighting, very useful but invisible, very similar to the concept of vitality.

*Martial Compilation First Collected Works, Chapter Five, Boxing, Tang Shunzhi (1507-1560), 武編前集, 卷五, 拳, 唐順之 (1507-1560)

**Selection of Records on War, Chapter One, Training, He Liangchen (1506-1600), 陳紀選, 卷一, 教練, 何良臣 (1506-1600)

***無形無像我的功