A New Theory of Numerology

• Type: Textbook
• Owners: Hermione Granger, third-year Arithmancy students at Hogwarts
• Maker: Unknown

A New Theory of Numerology is the required textbook for the third-year Arithmancy curriculum at Hogwarts School of Witchcraft and wizardry. The book is described as being very heavy and having a “very dull” appearance. Its contents are complex and academic, suitable for the advanced study of the magical properties of numbers.

As a textbook, the book's primary function is educational. It contains the core principles and advanced concepts of Arithmancy, a branch of magic that involves the complicated magical properties of numbers and is used as a form of divination. Students, such as Hermione Granger, use the text to complete challenging homework assignments and write long, difficult essays on the subject. The content is presumably dense, requiring intense concentration and study.

The publication history and author of A New Theory of Numerology are not mentioned in the novels. It was the prescribed text for Professor Septima Vector's Arithmancy class during the 1993-1994 school year. Hermione Granger purchased a copy from Flourish and Blotts in Diagon Alley before the start of her third year.

The book's presence in the narrative serves primarily to characterize Hermione Granger during her third year. It symbolizes her immense academic ambition and her willingness to take on the most challenging subjects offered at Hogwarts. The book is frequently mentioned as being part of the large, precarious piles of homework surrounding Hermione, highlighting the immense pressure she was under while secretly using a Time-Turner to attend all of her classes. Its most significant moment occurs near the end of the school year. After a stressful encounter with Professor Trelawney, an overwhelmed and frustrated Hermione storms back to the Gryffindor Tower common room, slams A New Theory of Numerology down on a table, and declares that she has dropped Arithmancy. This act marks a crucial point in her character development, as she finally acknowledges her limits and chooses her well-being and her friendships with Harry Potter and Ron Weasley over achieving impossible academic perfection.

• A prop for A New Theory of Numerology was created for the film adaptation of Harry Potter and the Prisoner of Azkaban. It can be seen among Hermione's books in various scenes (film).