It was an arcane magic book- not for beginners. It only took a few sentences before Mary was transfixed on the tome. She left her schoolwork aside and began reading the tome closely. Her mind was not prepared for the book and so she could only understand parts of it. When she looked at some paragraphs, the letters danced and she would stare at it confused until her mind suggested she move on.
Reading it, Mary learned the history of the arcane arts. Even early in human civilization there were those that could manipulate arcane energy, however these people sacrificed their sanity for those abilities and were barely sentient. Later on there were sorcerers that first mastered novice majicks before moving on to arcane studies. Although they sacrificed sanity like their predecessors, they were far more mentally healthy. During the Dark Ages, magicians were able to curse whole towns with the dark arts. Some of them were able to summon interdimensional monsters, although those never ended well. One arcane sorcerer transcended into a demon himself.
Mary finally broke out of the trance. It took a moment for her to realize what had just happened. She gasped rapidly. Drool was hanging from her lips. Her body was hot like she had a fever. And she looked down on her chair and realized she had peed herself quite thoroughly. She looked at the clock. For seven hours she was reading that book. With a trembling hand she pushed herself up. The squishiness in her panties indicated she shit herself too.
She couldn't say a word. Still shaken by the trance, she shambled to the washroom and turned on the bathtub. Not even taking off her clothes, she sat down in the water and soaked for what felt like hours until she had gathered her bearings and could assess what had happened.