The Sophist is a dialogue written by Plato, describing the nature of a Sophist. He uses this text to outline what a proper Sophist is and to differentiate them from a philosopher or politician, because there are some similarities. According to the definitions explored in the writing, a Sophist is a sort of moral and enlightened educator who teaches select students in the areas of ethics, philosophy, mathematics, language, rhetoric, and law, among other things. A Sophist, according to Plato, is more of a guide and counselor, one who attempts to impart excellence on his students. Let's look at a few quotes from the text to explore these ideas.

There is the purification of living bodies in their inward and in their outward parts, of which the former is duly effected by medicine and gymnastic, the latter by the not very dignified art of the bath-man; and there is the purification of inanimate substances—to this the arts of fulling and of furbishing in general attend in a number of minute particulars, having a variety of names which are thought ridiculous.

Here, the character Socrates, who is essentially narrating and explaining the idea, defines the ideas of purification, as that is the primary action of a Sophist. He claims that the Sophist is intending to offer purification and to teach the practices of purification to his pupils. The effective guide and scholar will teach things that help the body and mind—that is, medicine and fitness, as well as arts, reason, math, and science.

Then there are these two kinds of evil in the soul—the one which is generally called vice . . . and there is the other, which they call ignorance, and which, because existing only in the soul, they will not allow to be vice.

Socrates is explaining the types of "evil" the Sophist will remove from a pupil. By educating them thoroughly on law and reason as well as philosophy, the teacher helps to prevent their pupil from engaging in all types of vices and keep them upright and pure. Additionally, the teacher improves on the student's knowledge, removing ignorance from their soul so they can do more to live a better life and be more intellectual.

The common notion pervading all these objects, which you speak of as many, and yet call by the single name of image, as though it were the unity under which they were all included.

Here, Socrates is getting at the nature of Sophism in general: that it is many things wrapped into one that can't be easily expressed or dissected. He claims the Sophist takes many different forms and his education and guidance can't be easily separated out to follow one clear delineation, but he is still a purveyor of all types of learning and purification.