His Dark Materials by Philip Pullman

"His Dark Materials" is a fantasy trilogy that follows the journey of a young girl named Lyra Belacqua and her daemon, Pantalaimon, across parallel universes. Throughout their adventures, they encounter a variety of mythical creatures, confront religious and political systems, and grapple with complex themes such as free will, original sin, and the nature of consciousness. The series also delves into the mysteries of Dust, a strange particle integral to the multiverse's function.

The 225th greatest book of all time