The Book of the Imy-Duat (eg. “What is in the Hereafter”) is one of the several guides that describe the Netherworld. It depicts the journey that the deceased has to accomplish through the nocturnal sky on the boat of the god Re. its purpose is precisely to assist him in the dangerous night way that he must perform like the solar god. One of the main features of this book is its division in the twelve hours of the days and of the night and the description of the fight against the snake Apophis, that every night tries to devour the sun.