Think of a book as a chapter. It may be comprised of ten chapters, eleven.. maybe even 34, but, ignore all of that, take that all as decoration: it’s just a chapter.
Think of it as a chapter, a tiny snippet, a quick glimpse of a wider world. A snapshot. The world you’ve just submersed yourself in, the glimmer of the rich, expansive world that the author has granted you access to, existed long before the very first page, and will continue to exist, for eternity, long after you have turned the very last.
The beginning is secretly, not at all, the beginning. The characters have just taken time out of their schedules to notice you,the new-comer, and come over to introduce themselves; such as in the end. The end is never the end. The characters have fed you their chapter, their story, and given you a glimpse of what you needed to see. They’re now ready to continue living theur lives, in a world, their world, the world compressed by two, hard covers and tucked neatly into a space on your shelf, among other worlds: a galaxy.