Extremely original

This book is exciting! Like the main character, we ask a lot of questions to which the answers are gradually on the nature of the world described by the author. The writing is fluid, descriptions are clear, there is also an original way to combine the concepts of time and space.
Only small problem: the end, I found some "easy" and not enough convincing COMPARED to the rest of the novel, and that made me hesitate between 4 and 5 stars.
That said, this book MUST be among the classics of science fiction.