Nèijiā

The term "nèijiā" usually refers to the internal styles of Chinese martial arts, which Sun Lutang identified in the 1920s as T'ai Chi Ch'uan, Xíngyìquán and Bāguàzhǎng. This classifies most other martial arts as "wàijiā" (lit. "external/outside sect"). Some other Chinese arts, such as Liuhebafa and Yiquan are frequently classified (or classify themselves) as internal or having internal qualities. These secondary neijia may be related to, or derived from, the primary arts.

Criteria for distinguishing the neijia arts
Sun Lutang identified the following as the criteria that distinguish an internal martial art:
 * 1) An emphasis on the use of the mind to coordinate the leverage of the relaxed body as opposed to the use of brute strength.
 * 2) The internal development, circulation, and expression of qì.
 * 3) The application of Taoist dǎoyǐn, qìgōng, and nèigōng (內功) principles of external movement.

Sun Lutang's eponymous style of T'ai Chi Ch'uan fuses principles from all three arts he named as neijia. Some Chinese martial arts other than the ones Sun named also teach what are termed internal practices, despite being generally classified as external (e.g. Wing Chun). Some non-Chinese martial arts also claim to be internal. e.g. Aikido, I Liq Chuan, Ip Sun, and Kito Ryu jujutsu. Many martial artists, especially outside of China, disregard the distinction entirely. Some neijia schools refer to their arts as "soft style" martial arts.

Earlier classification
The term "nèijiā" and the distinction between internal and external martial arts first appears in Huang Zongxi's 1669 Epitaph for Wang Zhengnan. Stanley Henning proposes that the Epitaph's identification of the internal martial arts with the Taoism indigenous to China and of the external martial arts with the foreign Buddhism of Shaolin—and the Manchu Qing Dynasty to which Huang Zongxi was opposed—was an act of political defiance rather than one of technical classification.

In 1676 Huang Zongxi's son, Huang Baijia, who learned martial arts from Wang Zhengnan, compiled the earliest extant manual of internal martial arts, the Nèijiā quánfǎ.

Characteristics of neijia training
Internal styles (內家) focus on awareness of the spirit, mind, chi (breath, or energy flow) and the use of relaxed leverage rather than unrefined muscular tension, tension that soft stylists call "brute force". Pushing hands is a training method commonly used in neijia arts to develop sensitivity and softness.

In recent years, many of "New Age"-oriented schools have appeared, which traditionalists criticize for emphasizing philosophy and speculation at the expense of hard work. For this reason, and because in most internal schools beginning students are expected to work on very basic principles for an extended period of time, many people believe internal styles lack "external" physical training. In the older schools, this is usually not the case. Much time may be spent on basic physical training, such as stance training (zhan zhuang), stretching and strengthening of muscles, as well as on empty hand and weapon forms which can be quite demanding. Also, many internal styles have basic two-person training, such as pushing hands and duet forms.

Some forms in internal styles are performed slowly, although some include sudden outbursts of explosive movements (fa jing), such as those the Chen style of Taijiquan is famous for teaching earlier than some other styles (e.g. Yang and Wu). The reason for the generally slow pace is to improve coordination and balance by increasing the work load, and to require the student to pay minute attention to their whole body and its weight as they perform a technique. At an advanced level, and in actual fighting, internal styles are performed quickly, but the goal is to learn to involve the entire body in every motion, to stay relaxed, with deep, controlled breathing, and to coordinate the motions of the body and the breathing accurately according to the dictates of the forms while maintaining perfect balance.

Differences between internal and external arts
The reason for the label "internal," according to most schools, is that there is a focus on the internal aspects earlier in the training, once these internal relationships are apprehended (the theory goes) they are then applied to the external applications of the styles in question.

External style (外家, pinyin: wàijiā; literally "external family") are characterized by fast and explosive movements and a focus on physical strength and agility. External styles include both the traditional styles focusing on application and fighting, as well as the modern styles adapted for competition and exercise. Examples of external styles are Shaolinquan, with its direct explosive attacks and many Wushu forms that have spectacular aerial techniques. External styles begin with a training focus on muscular power, speed and application, and generally integrate their qigong aspects in advanced training, after their desired "hard" physical level has been reached.

Quotes about Neijia
The Yang family of T'ai Chi Ch'üan is known to have possessed documents describing their opinions on internal and external martial practice at least as far back as the second half of the 19th century. In these writings attributed by the Yang family to Zhang Sanfeng and known by modern scholars as the "Forty Chapters" the distinction is mentioned in the twentieth chapter:

"As a martial art, T’ai Chi is externally a soft exercise, but internally hard, even as it seeks softness. If we are externally soft, after a long time we will naturally develop internal hardness. It’s not that we consciously cultivate hardness, for in reality our mind is on softness. What is difficult is to remain internally reserved, to possess hardness without expressing it, always externally meeting the opponent with softness. Meeting hardness with softness causes the opponent’s hardness to be transformed and disappear into nothingness. How can we acquire this skill? When we have mastered sticking, adhering, connecting and following, we will naturally progress from conscious movement to interpreting energy and finally spiritual illumination and the realm of absolute transcendence. If our skill has not reached absolute transcendence, how could we manifest the miracle of four ounces moving a thousand pounds? It is simply a matter of “understanding sticky movement” to the point of perfecting the subtlety of seeing and hearing."

Wu Jianquan wrote on the subject as well at the beginning of the 20th century:

"Those who practice Shaolin Ch'uan leap about with strength and force; people not proficient at this kind of training soon lose their breath and become exhausted. T'ai Chi Ch'uan is unlike this."

"The greatest taboo when practicing T'ai Chi Ch'uan is to use force. If one can make the entire body loose and open ... then after a while one's practice will naturally develop inner ching. This inner energy is extremely soft, so when encountering an opponent one doesn't need to resist at all. The ability to extend and contract in order to follow the opponent's energy is referred to as elastic/tensile power within softness. T'ai Chi Ch'uan theory states: "From the greatest softness comes the greatest hardness." This is what is meant by softness."

Current practice of neijia arts
Today, only a few traditional schools teaching internal styles train martially. Most schools teach forms that are practiced for health benefits only, as this is in higher demand. To condition oneself well enough to become adept at the internal style martial arts is a long-term proposition; many simply lose interest after a few years and never continue the practice. Many people who have not fully learned the martial aspects of their style teach publicly anyway, leading to a further diminution of the martial applications taught in many schools. Some instructors supplement what they are teaching with elements from other martial arts and their training becomes further diluted. Many health-oriented schools and teachers believe that the martial practices of neijia are no longer necessary in the modern world, as well as claiming that students may not need to practice martially to derive a benefit from the training. Traditionalists feel that a school not teaching martial aspects somewhere in their syllabus cannot be said to be actually teaching the art itself, that they have accredited themselves prematurely. Traditional teachers also believe that understanding the martial theories and the ability to apply them are a necessary gateway to health benefits.

Neijia in fiction
Internal styles have been associated in legend and in much popular fiction with the Taoist monasteries of Wudangshan in central China.

Neijia are a common theme in Chinese Wuxia novels and films, and are usually represented as originating in Wudang or similar mythologies. Often, genuine internal practices are highly exaggerated to the point of making them seem miraculous, as in Crouching Tiger Hidden Dragon or Tai Chi Master. Internal concepts have also been a source of comedy, such as in the films Shaolin Soccer and Kung Fu Hustle.