The "darkness" of the title is a multifaceted symbol. It represents the unknown jungle, the cruelty of the colonizers, and the potential for evil in every person. Marlow's journey is a quest to understand this darkness. Readers who want to explore these layers of meaning often find a Heart of Darkness PDF to be the most convenient format. The novella is a compact but heavy read, packing a lifetime of philosophical inquiry into a short narrative. It is a book that changes the way you see the world.