|"Is this all real? Or has this been happening inside my head?"
The topic of this article is of a real-life subject that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really existed), and, as such, details contained in this article may differ from real world facts.
Hermetray was an island in the Hebrides. After leaving Hogwarts School of Witchcraft and Wizardry out of protest at the young age of fourteen, Zygmunt Budge, considered an eccentric wizard, chose to live on this remote island. Here, he would conduct various potion experiments, eventually writing his masterwork Book of Potions.