The following is part of an upcoming article that was posted by Wuyizidi on this thread over at EF. I think it is a good, basic overview of the shifu/tudi relationship, although it represents a certain POV. I have heard some different things than the article below suggests, but it seems to be a good general discussion of the main points.
2.3 Master and disciple
The relationship between the master and the disciple is a very special one within the martial arts family system. It is different from a regular teacher student relationship. Within this relationship, a master and his disciple are not only a teacher and a student, but also a father and a son. In traditional way, no one can get real high-level skills from another person before they formally enter into this kind of relationship. This is the foundation of the martial arts family system.
Master is Shi Fu. Shi means master or teacher, Fu means father. So a Shi is someone who has the duties of both a teacher and a father. As a teacher, a She Fu has duty to teach, which consists of three things: 1) Chuan Dao - transmit the meanings of Dao, here that includes martial virtues and in addition to meaning of life; 2) Shou Ye - teaching martial arts skill and knowledge; and 3) Jie Huo - answering questions, clarify confusions. And as a father, the Shi Fu has the duty to take care his disciple as if he is his own son, according to tradition this covers all aspects of the students life.
Disciple is Tu Di. Tu means journeyman, someone who has not arrived at his goal or destination yet, so Tu also means emptiness or nothing. Di is younger brother, so it implies lower level. Together Tu Di means one who knows nothing and is in lower level position, needing to study, or on a path of learning. Another common word for disciple is Di Zi, Zi meaning son. Sometimes to be perfectly clear and emphasize the fact that the student is a formal disciple in the traditional sense, because it’s not uncommon for a regular student (non-disciple) to be called Tu Di in informal manner, one can be called Ru Men (inside the door) or Ru Shi (inside the room) Tu Di.
Why did people need to set up this type of relationship within the groups? There are four main reasons:
First, martial art knowledge is like a dangerous weapon, it can be used to do both good and evil. So the access and use of that knowledge must be carefully controlled. In tradition way, a teacher had no right or duty to control his students’ behaviors, but a master had these rights over his disciples. When a disciple does something wrong, people expect his master to take some responsibility. So a bad disciple can cause major trouble for his master. People thought that only when a master can really trust a student and accept him as a disciple, he can control the disciple’s behavior and then can teach him high-level skills.
Second, the group’s reputation. If someone does some bad things, it does not only affect his own reputation also create bad reputation for the group as a whole. So a master would take time evaluating the student’s personality. If he has doubts, the master can reject him as a disciple. In that case the master and the group would not take responsibility for this student’s behaviors.
Third, teaching martial arts techniques is a very special process, especially for high-level skills. There is only one way to accomplish this, a process called ‘Kou Chuan Xin Shou’, meaning teaching skill face-to-face and heart-to-heart. Other things can also help, but nothing can take its place. In high-level skill training, the most important things are the changes occurring on the inside and the associated feelings. These things can only be explained when two persons touch each other. Without touching, nobody can really know these. When a master teaches his student these things, he must show his skills by touching his student. Then in turn he must allow his student to touch him, so he can see if the student is right or wrong. Sometimes, to make it easier for the student to understand a skill, the master will not make changes to his movement or position, not even to protect himself. This is of course a very dangerous situation for the master. He is, without any protection, a target for the student. If a master does not fully trust this student, he would not want to do this. Also, this method demands a lot of energy from the master, there will be lost of Qi on his part. So it is also very physically taxing for the master to teach in this way. Because of these reasons, usually a master does not like to teach everyone in this manner, so that it is why people always say that a master would only teach high-level skill to his disciples but not regular students.
Fourth, this relationship help make sure people will really look after each other. The young need education and training, the old need care and support in their advanced ages. When a disciple is young, he needs training from his master. When a master gets older, he needs his disciples to take care of him. This is a very traditional idea. People think the most fortunate thing that can happen to a person is that he has children or disciples that can look after him when he gets older. Regular students have no duty to do this, but disciples have responsibilities not just as students but also sons. Sometimes a master may have no children, and he is dependent only on his disciples, like the great Bagua master Dong Haichuan. After retirement, he lived in his disciple and granddisciple’s homes until he passed away.
Lehrer, Sifu, Meisterschüler, Meister ...
Zitat von Swizzfighter
) gab es in den meisten Systemen (auch in den japanischen!) keine Rangeinteilung der Schüler. Die von dir aufgeführten Bezeichnungen sind eher "de facto"-Ränge. Will heißen: Der Leiter der Schule, der damit ja auch oberster Lehrer war, wurde mit Meister angesprochen, sein Meister war eben der Großmeister (siehe Vater -> Großvater). Die Leute, die dem Meister beim unterrichten halfen, waren die "Lehrer" oder "Übungsleiter". Die Schüler waren eben "Schüler". Die paar Schüler, die "die Besten" waren, wurde als "Meisterschüler" bezeichnet. Das war entweder so, weil sie eben die "Meister unter den Schülern" waren, oder weil der Meister sich persönlich besonders intensiv um sie kümmerte. 
