Page numbering of introduction in a thesis In English literature, it is common to use roman page numbering for the preface and then the Arabic for the actual content of a given book. Then, should the introduction belong to the preface or not? My impression is that, in case of books, the introduction is usually paginated roman, while in theses, it has usually already the Arabic numbers. I am aware this may not be so important. Although, I suppose this rule has some reason; therefore I am wondering, what exactly is this reason?

(I am finishing my thesis now. That's why I ask. Our university does not have any rules regarding this.)
It depends what you mean by introduction. 

If your introduction is similar to introductions found in research manuscripts, then the introduction is part of the main body and should use Arabic numbering. On the other hand, if your introduction is metadata, then the introduction is part of the front matter. (Metadata introductions are common in textbooks.)

That said, first and foremost, you should follow your institutes required style.