These rules govern the use of the Traditions.
Sorcerers form cabals, schools, guilds and cults. Not only does this give them social benefits and venues for finding teachers, students and employment. Nor is it solely because they wish to form a school of magic and gather together all the lore they can find. No, a major reason is that they need the support of their fellows when confronting the raw forces of reality.
Sorcery is the art of shaping reality through your craft. It is similar to Shaping, but much more commonly available, and more utilitarian. But all sorcery deals with reality on a very primal level, and all sorcerers need a solid root in tradition in order to manipulate reality in this way.
A magic tradition is always based on a particular view of reality and the sorcerers place in that reality. Many such traditions are based in religion. Some assume that the sorcerer is a servant of some divine force, which grants him his power. Others seek to manipulate or plead with the divine forces of the universe without devoting themselves to serving them. Yet others see the universe as impersonal and the strings they pull as simple cause-and-effect relationships with no deeper meaning. But however sorcerers describe reality, they must be very devoted to their point of view; it is the fixed point that gives them the leverage to move the universe.
A world-view that is shared between several sorcerers is easier to use and becomes more powerful. The sorcerer can convince himself of the validity of his views by comparing his works and theories to those of others in the same tradition. Breaking with tradition is iconoclastic and heretical, and might very well prompt his former colleagues to hunt him back or kill him rather than let him leave the fold. They have to; failing to do so would weaken their own confidence in the magic they are using.
It is possible to establish your own sorcery tradition, with your own strictures and limitations. But doing so is an immense undertaking, and you can expect hostility from existing schools and no help when learning new magic. This is something best left to semi-mythical NPCs. Each sorcery tradition has some limitations, crutches or mental obstacles that you must accept in order to use sorcery. Certain sorcerers do away with one or more of these crutches, but only with great effort. These are the Limitations of sorcery, rules that are central to your world-view and can only be broken under dire duress. These Limitations are unlike those of other types of Schticks in that they are more style oriented than actual flaws; they require a good deal of GM judgment and role-playing skill to be meaningful.
Whenever you break one of these strictures, you suffer a -5 penalty to your Sorcery. You do not get multiple penalties for breaking multiple strictures - once out of bounds, anything goes.