The Complete Secret of Applications (全體大用訣) by Yáng​ Bān​hóu​ (楊班侯)

全體大用訣

太極拳法妙無窮，掤捋擠按雀尾生。
斜走單鞭胸膛佔，回身提手把招封。
海底撈月亮翅變，挑打軟肋不容情。
摟膝拗步斜中找，手揮琵琶穿化精。
貼身靠近橫肘上，護中反打又稱雄。
進步搬攔肋下使，如封似閉護正中。
十字手法變不盡，抱虎歸山採列成。

楊班侯

"The techniques of Tai chi chuan are marvellous and unlimited. It produces Peng, Lu, Ji, An and Grasp the Sparrow’s tail.
Walk diagonally into Single Whip to occuppy the chest area. Return the body and lift arms to seal the center.
Pick up the Moon from the Bottom of the Sea and vary it into the Spread the Wings. Use the picking hand to attack the soft tendons (lower part of the rib) without mercy.
The application of Brush the Knee and Step Forward is found diagonally. The variations of poking in Hands Like Pi Pa are essential.
When the body is closed (to the opponent), use the sideways elbow to attack. This will protect the center and allow to use the reverse fist strike to become an hero again.
Step forward for Parry and Punch, apply it to the lower ribs. As Seal as Close is used to protect the center.
The variations of Cross Hands techniques are unlimited. Embrace the tiger to return to the Mountain to complete the Pluck (Cai) and Split (Lie)."

肘底看捶護中手，退行三把倒轉肱。
墜身退走扳挽勁，斜飛招法用不空。
海底針要躬身就，扇通臂上托駕功。
撇身捶打閃化式，橫身進前招法成。
腕中反有閉拿法，雲手三進臂上功。
高探馬上攔手刺，左右分腳手要封。
轉身蹬腳腹上佔，進步栽捶迎面沖。

"In Punching under the Elbow there is a hidden hand for protection. Step Back Three Times and Reverse the Forearm to sink the body for retreating and twisting force.
The technique of Diagonal Flying can be used often without being in vain.
To execute Pick Up the Needle from the Bottom of the Sea the body should bow accordingly. Fan back can be achieved by pressing and supporting upward.
Turn, Twist Body and Circle the Fist is a posture of dodging and neutralizing. The body should advance from sideways to accomplish this technique.
There are techniques of sealing and sizing hidden in the wrist with reverse action. Attach the arm with Wave Hands like Clouds three times.
Stand High to Search Out the Horse is used to intercept the coming poking hand. When applying the Left and Right Separate Foot, the hands must seal (the opponent’s attack clearly).
Turn and Kick with the Heel is used to attack (the opponent’s) abdomen. (When using) Stepping Forward and Strike Down with the Fist, thrust towards the opponent directly."

反身白蛇吐信變，采住敵手取雙瞳。
右蹬腳上軟肋踹，左右披身伏虎精。
上打正胸肋下用，雙峰貫耳招法靈。
左蹬腳踢右蹬式，回身蹬腳膝骨迎。
野馬分鬃攻腋下，玉女穿梭四角封。
搖化單臂托手上，左右用法一般同。
單鞭下勢順峰入，金雞獨立佔上風。

"Turn the body, use the White Snake Spits Poision to change the situation. Plucking the opponent’s hand and attacking his two eyes.
The Right Heel Kick is used to tread soft ribs. Left and right dodging the body, the technique of Taming the Tige ris refined.
The upper hand is to strike the ribs at the lower chest (solar plexus). The technique of Attacking the Ears with the Fists is effective.
Left Heel Kick is used to defend against the opponent’s right heel kick. Turn the Body and Kick with the Heel is aiminig at the knee cap.
The Wild Horse Parts its Mane is to attack the place under the armpit. The Fair Lady Weaves with Shuttle is used to seal the four corners.
Use the single arm to neutralize the incoming force and the other hand to attack upwards. The applications of the left and right are all the same.
Single Whip to Snake Creeps Down is to follow the incoming force and enter. Use the Golden Rooster Stands on One Leg to occupy the advantageous position."

反身白蛇吐信變，采住敵手取雙瞳。
右蹬腳上軟肋踹，左右披身伏虎精。
上打正胸肋下用，雙峰貫耳招法靈。
左蹬腳踢右蹬式，回身蹬腳膝骨迎。
野馬分鬃攻腋下，玉女穿梭四角封。
搖化單臂托手上，左右用法一般同。
單鞭下勢順峰入，金雞獨立佔上風。

"Turn the body, use the White Snake Spits Poision to change the situation. Plucking the opponent’s hand and attacking his two eyes.
The Right Heel Kick is used to tread soft ribs. Left and right dodging the body, the technique of Taming the Tige ris refined.
The upper hand is to strike the ribs at the lower chest (solar plexus). The technique of Attacking the Ears with the Fists is effective.
Left Heel Kick is used to defend against the opponent’s right heel kick. Turn the Body and Kick with the Heel is aiminig at the knee cap.
The Wild Horse Parts its Mane is to attack the place under the armpit. The Fair Lady Weaves with Shuttle is used to seal the four corners.
Use the single arm to neutralize the incoming force and the other hand to attack upwards. The applications of the left and right are all the same.
Single Whip to Snake Creeps Down is to follow the incoming force and enter. Use the Golden Rooster Stands on One Leg to occupy the advantageous position."

Based on the translation by Yang Jwing Ming (楊俊敏) presented in the book Tai Chi Secrets of the Yang Style (太極拳楊氏先哲秘要)

Excerpt from Weak and Strong Points (謀攻) in The Art of War (兵法)

凡先處戰地而待敵者佚，後處戰地而趨戰者勞。故善戰者，致人而不致于人。能使敵人自至者，利之也；能使敵不得至者，害之也。

孫子

"Whoever is first in the field and awaits the coming of the enemy, will be fresh for the fight; whoever is second in the field and has to hasten to battle will arrive exhausted. Therefore the clever combatant imposes his will on the enemy, but does not allow the enemy's will to be imposed on him. By holding out advantages to him, he can cause the enemy to approach of his own accord; or, by inflicting damage, he can make it impossible for the enemy to draw near."

Unless noted otherwise, all quotations of classical texts and accompanying translations come from the Chinese Text Project

A Study of Xing Yi Quan (形意拳學) by Sūn Lùtáng (孫祿堂) translated by Albert Liu

This is certainly the reference book on Xíngyìquán (形意拳). The author, Sūn Lùtáng (孫祿堂) is one of, if not the, main masters of internal martial arts in the 20th century. For this aspect alone, it would be a key book for the practicioner.
As a manual, it is a rather complete coverage of the main basic aspects of the art. To my knowledge is one of very the few books that go beyond the Five Fists (五行拳) to the Twelve Animals (十二形拳) of Hebei and Anshenpao (安身炮). Each movement is presented with a "theoretical explanation", to me the most interesting parts, followed by the movements themselves, which are always better seen with a qualified teacher than in a book.
The main interest is that Sūn Lùtáng (孫祿堂) developed the main systematization of the Internal Martial Arts(內家). In his books for the first time cosmological taoist terms like Wú​jí (無極), Tài​jí (太極) and Liǎng​yí (兩儀) are presented to explain specific steps of the practice. Even though it is applied to the other internal arts, this systematization is particularly striking for Xíngyìquán (形意拳).

The Secret

練

Within the Internal Martial Arts lore, there is an anedocte that highlights the importance of practice. It says that when Sūn Lùtáng (孫祿堂) was on his deathbed, his students asked him what was the secret for reaching a high level of Kung Fu. As Sūn Lùtáng was unable to speak, he raised his palm and with the other hand, drawn an imaginary character "practice" - liàn (練) on it.
In the introduction of the translation of Study of Xing Yi Quan (形意拳學) by Benjamin Lo, Sūn Jiànyún (孫劍雲), Sūn Lùtáng's daughter, states that the story is apochryphal and false. She goes on to say that it does convey the opinion of Sūn Lùtáng nevertheless. This is also an observation that I had from any serious teacher.
It is a fine reminder of the prime place of practice (練), relegating any other activity to a secondary place. Activity as reading books, watching videos, or writing this blog for that matters, are diversions to the one core activity of the serious practicioner.
However, the story stops short of giving further clues of what should constitute practice: its scope (what kind of exercices? how many styles?), the relative importance of frequency and quantity, how much practice is enough, under what conditions it is wise to practice and not practice, and so on. Some of the more esoteric aspects are sometimes adressed, like the notion of practicing facing north or early in the morning, without however a general orientation on how to practice.
In fact, what I would call the methodology of practice is something that is not systematically approached in the literature and in classes in general. It is particularly hard for a beginner to find himself all alone and decide what she should practice. In my opinion, this point is the main first obstacle for someone that wishes to become a serious practitioner.

Eight Vital Points (八要) by Jiāng Róngqiáo (薑容樵)

八要

心定神寧，神寧心安，心安清淨。清淨無物，無物氣行、氣行絕象，絕象覺明，覺明則神氣相通，萬氣歸矣。

薑容樵

"If the mind is settled, then the spirit is peaceful. If the spirit is peaceful, then the mind is calm. If the mind is calm, then it is pure and clear. If it is pure and clear, then there is nothing. If there is non content, then the qi moves. If the qi moves, then the form disappears. If the form disappears, then awareness and understanding raise. With awareness and understanding, the spirit and qi will connect. Then all of the qi’s will return."

From the book Xing Yi Mother Fists (形意母拳), by Jiāng Róngqiáo (薑容樵), based on the translation by Joseph Crandall

The Study of Wuji in the Sword (無極劍學) from the Study of Bagua Sword (八卦劍學)

無極劍學

劍學之無極者，當人執劍身體未動之時也，此時心中空空洞洞混混沌沌一氣渾然，此理是一字生這〇，一字者先天之至道，這〇者無極之形式，是先天一字之所生。人生在世，未嘗學技動作自然，是道之所行，是一字也。及手執劍正立身體未動，是一字生這〇也。譬諸靜坐功夫，未坐之時，呼吸動作是先天道之自然之所行，如同一字也。甫坐之時，兩腿盤跌兩目平視，雖未垂簾觀玄兩手打扣，而心中空空洞洞無思無想一氣渾然，如同〇也。及心神定住，再扣手垂簾塞兌觀玄，又如同這矣。所以劍學與丹道，初無差別，分之則二合而為一，是即劍學無極之理，天地之始也。或者丹書雲：道生虛無，返回練虛合道，是此意也。學者細參之，此理大中秘密言之。

孫祿堂

"The study of Wuji in the sword refers to a man standing and holding the sword, and his body not yet moving. At this moment the center is empty and formless, the unified qi is undivided. This principle is represented by an empty circle, this character (the circle) and the pre-natal heaven follow the same way. The circle is the form of Wuji, it is the symbol of the creation of the Pre-natal. When people are born into the world, before they had learned skills, their natural movements are spontaneous in the Taoist way. When one holds the sword and stands up before the start of the movement, the symbol of the circle is generated.It is like doing sitting meditation, without sitting. Breathing is natural as the pre-natal dao, as the symbol (circle). At the time of sitting, both legs drop and both eyes look levelly ahead. Although you are not blindfolded, you still see the darkness, both hands closed. The interior is empty; there are no thoughts, no consideration, the one qi is undivided as the circle. The attention is still, again the hands turn inward and hang like a curtain, stop looking, this is like a dot in a circle. There is no difference between the study of the sword and the Daoist alchemy, the two are one. The principles of Wuji in the study of the sword are the same of those of the beginning of the world. The Dan Shu says “the Dao is born out of empty nothing, the practice of returning joins the Emptiness to the Dao”, this is the meaning. The student must pay detailed attention; this principle is one of the major secrets."

起點面正，身子直立不可俯仰，兩手下垂直，兩足為九十度之形式。右手執劍，手為中陰中陽之訣式，劍尖與劍把橫平直，左手五指伸直手心靠著腿，兩手兩足不可有一毫之動作。心中空空洞洞，意念思想一無所有，兩目望平直線看去，亦不可移轉，將神氣定住。此式自動而靜由一而生這〇，即為無極形式，內中一切情形與八卦拳學無異，此道執械則為劍，無械即是拳，所以八卦拳學於各種器械莫不包含，學者可與八卦拳并參之。

"The starting point is to look upright. The body stands upright, it should not pitch forward or backward. Both hands hand down straight. The feet form a 90 degree angle. The right hand holds the sword. The hand shape middle Yin middle Yang is the secret. The point of the sword together with the sword handle are leveled. The five fingers of the left hand are stretched out, the palm is near the leg. Neither hands nor feet should have one bit of movement. The mind is empty. There are not thoughts at all. Both eyes gaze at the horizon. The sight is set at the distance, it does not wander around. The vitality shall be present. This form is naturally moving and yet still, one is born from zero, this is the Wuchi form. In all circumstances it is part of the Study of Bagua Quan. This is the way to hold a weapon and make it function as a sword. Because the study of the fist is without weapon, the study of Bagua Quan includes all kinds of weapons. The student can combine (the study of the sword) with Bagua Quan."

From the book The Study of Bagua Sword (八卦劍學), by Sūn Lùtáng (孫祿堂), based on the translation by Joseph Crandall

The Explanation of Tai Chi Chuan's Harmonious Stepping in Four Sides of Pushing Hands (太極拳合步四正推手解)

太極拳合步四正推手解
太極拳以練習推手為致用，學推手刖即是學覺勁,有覺勁刖懂勁便不難矣。故總論所謂由懂勁而階及神明，此言即根於推手無疑矣。掤，履，擠，按四式即黏，連，貼，隨捨己從人之定步推手。

楊澄甫

"Taijiquan uses the practice of pushing hands because of its delicate appplication. Learning pushing hands means learning Feeling Jin. When there is Feeling Jin, the Understanding Jin is not difficult. Therefore, the Total Thesis (of Taijiquan) said: «from Understanding Jin then gradually reach the spiritual enlightenment». There is no doubt that these words are in the basis of pushing hands. Peng (Ward Off), Lu (Rollback), Ji (Press), and An (Push) are the four patterns of adhering, connecting, attaching and following of selfless yielding in fixed-step push hands."

Dictated by Yang Chengfu (楊澄甫口述), noted by Chen Weiming (陳微明筆述), based on the translation by by Yang Jwing Ming (楊俊敏) presented in the book Tai Chi Secrets of the Yang Style (太極拳楊氏先哲秘要) and various translations on the internet

Three Emptinesses

The term "Empty" or "Emptiness" is often used in Internal Martial Arts (内家武術) translations, in particular those that are somewhat older. In fact, whenever reading a text that mentions "emptiness" in a western language one should be aware that it can point to three different notions.

空

The first translation is what I would call "literal" emptiness, the notion that something has been emptied, is vacant, unoccupied. This term is kōng (空), and it describes a wide range of things: the outer space in astronomy (太空), the vacuum (真空), a cavity (空洞), a vacancy (空缺) or a "liberty" in the game of go.

In the internal martial arts texts I've seen, this term is used mostly linked to physical postures, like the necessity of emptying the chest. For example in "Cover" (扣) from the "Xingyi Eight Characters Secret" (形意八字訣) by Jiāng Róngqiáo (薑容樵):

一。兩肩要扣，則前胸空闊，氣力到肘。

"Both shoulders should be like covers. The chest is empty and broad. The qi strength arrives in the elbows."

虚

A second translation is mostly in Tai Chi Chuan (太極拳), and it relates to the way movement is made in Tai Chi. Earlier translations would talk about "full" (實) and "empty" (虚) for the weight for example. I think a better translation for this "fullness" and "emptiness" is given by Yang Jwing Ming (楊俊敏): "substantial" (實) and "insubstantial" (虚). The idea of emptiness here is an idea of void, often in what in the West would be seen as a negative sense: a false reputation (虚名), vanity (虚荣心) or fictitious or theoretical (虚拟). In the Tai Chi Chuan texts, the term is quite central to the practice, for example in the The Ten Important Points of Tai Chi Chuan (太極拳十要) by Yáng Chéngfǔ (楊澄甫):

太極拳術以分虛實為第一義

"The discrimination of insubstantial and substantial is the most important content in Taijiquan. "

無
極

Although much more rarely, the third term that is sometimes translated as "emptiness" or a related term is Wú​jí (無極). It is a term related to chinese cosmogony, as it refers to the potential state the universe was before the "Ten Thousand Beings" appeared (萬物). In internal martial arts, Wú​jí is used to denote the initial undifferentiated state, before a form is started. In some old translations or internal martial arts books, we would see "emptiness" or "empty oneself" related to that specific point.

The term has been introduced in the Internal Martial Arts universe by Sūn Lùtáng (孫祿堂) and Jiāng Róngqiáo (薑容樵), in texts like "The Song of Wújí" (無極歌) by Jiāng Róngqiáo (薑容樵) and "The Study of Wuji in the Sword" (無極劍學) by Sūn Lùtáng.

Chapter 36 (三十六) from the Dào​dé​jīng (道德經)Capítulo 36 (三十六) do Dào​dé​jīng (道德經)

三十六

將欲歙之，必固張之。
將欲弱之，必固強之。
將欲廢之，必固興之。
將欲奪之，必固與之。
是謂微明。
柔弱勝剛強。
魚不可脫於淵，
國之利器，不可以示人。

老子

"When one is about to take an inspiration, he is sure to make a (previous) expiration;
when he is going to weaken another, he will first strengthen him;
when he is going to overthrow another, he will first have raised him up;
when he is going to despoil another, he will first have made gifts to him.
This is called 'Hiding the light.'
The soft overcomes the hard; and the weak the strong.
Fishes should not be taken from the deep; instruments for the profit of a state should not be shown to the people."

Unless noted otherwise, all quotations of classical texts and accompanying translations come from the Chinese Text Project

"Para querer iniciar o recolhimento
É necessário consolidar a expansão
Para querer iniciar o enfraquecimento
É necessário consolidar o fortalecimento
Para querer iniciar o abandono
É necessário consolidar o amparo
Para querer iniciar a subtração
É necessário consolidar o aumento
Isto se chama breve iluminação
O suave e o fraco vencem o rígido e o forte
Os peixes não podem separar-se do lago
O reino que tem o instrumento afiado
Não pode colocá-lo à vista do homem"

Tradução de Wǔ Rǔqīng (武汝清)

The Song of Six Coordinations (六合歌) by Jiāng Róngqiáo (薑容樵)

六合歌

身成六式，
雞腿龍身，
熊膀鷹爪，
虎抱雷鳴。

薑容樵

"The whole body has six forms,
Cock legs, dragon body,
Bear arms, eagle claws,
Tiger’s embrace and the sound of thunder.

From the book Xing Yi Mother Fists (形意母拳), by Jiāng Róngqiáo (薑容樵), based on the translation by Joseph Crandall