A Rough Sketch of the World of Thalaba
an excerpt

Sorcery is the branch of magic concerned with the conjuration and control of spiritual beings or entities. Sorcery itself is neither good nor evil; like wizardry, it can be turned to any end, depending entirely upon the practitioner and his intent.

A sorcerer needs a good mind, not to harness the raw energies of magic, but to learn and understand the multifarious lore of conjuration -- all the various types and ranks of spirits, their names, their powers and abilities, how to identify them, and ultimately how to summon and command them. Exalted levels of intellectual genius are not required, simply an above-average understanding and a well-trained memory, together with enough concentration and strength of will to enable the sorcerer to apply himself to the course of study.

In theory, a sorcerer can carry out any conceivable magical intention, as long as he can conjure a spirit that can perform the task, and provided he can control the being once it has been conjured. The more powerful the entity, the more it is able to do, but the more difficult it is to control. Generally speaking, spiritual beings are not naturally cooperative, since they have other things to do and usually resent being interrupted by the sorcerer’s summons. A very well-disposed spirit might not mind performing a small task that is clearly related to the spirit’s own nature and interests. A neutrally inclined spirit will simply seek to get away if it can. A more malign spirit may seek to inflict punishment on the sorcerer for his impertinence. It is therefore imperative for the sorcerer to be able to control the spirit and compel it to do his bidding.

A sorcerer’s activity falls into four parts. First is conjuration, the summoning of the spirit to appear in the sorcerer’s presence. This is accompanied or followed by constrainment, also called trapping, which prevents the spirit from leaving or doing any harm once it has appeared. The third step is commanding the spirit to perform the desired task. The final step is dismissal, or giving licence to depart, in which the spirit (having completed its task) is allowed to leave but not allowed to do any harm.

Spirits are conjured and controlled mainly by the use of words and sigils, less often by gestures or material components. Summoning is done primarily by incantation, calling the spirit by name and adding certain words which invite, persuade, or compel it to appear. Materials such as herbs, blood, salt, or incense may be used to provide greater attraction. Once the spirit appears, it is typically constrained within an enchanted circle, triangle, or pentagram drawn on the floor. The sorcerer himself is normally protected within a similar circle. The spirit is then addressed and commanded in words, sometimes with the addition of gestures, and by the presentation of sigils. These incantations and sigils serve as passwords to which the spirit is innately bound to comply. Dismissal of the spirit is done in a similar manner.

The greatest danger in sorcery is that an incantation may be wrongly spoken, a name wrongly pronounced, or a sigil wrongly drawn. Any mistake in the procedure means that the spirit is not properly controlled or the sorcerer is not protected. An uncontrolled spirit might simply leave, or if it is of malign intent it may seek to harm the sorcerer. Particularly cunning or mischievous spirits are known to have pretended to be controlled, only to turn on the sorcerer when his guard was down.

Sorcerers do not form such a tight-knit community as wizards, but at the same time there is much less competition between them. Exceptionally talented sorcerers are likely to be supported, like wizards, by patronage. Lesser ones are often able to support themselves as "freelances", taking private clients. Some fall back on simple fortune-telling, holding seances, and the like, and some of these become outright charlatans, since fakery is both easier and safer than actual conjuration of spirits. Because the training involved is less demanding than that of wizardry, many sorcerers are able to support themselves by some other trade or craft. Some pursue sorcery only as a part-time interest, or retire from active sorcery in order to make a living at other work.