of His Dark Materials'', scientists in Cittagazze had created the Subtle Knife, which allowed them to travel between worlds. However, explorers were not meticulous about closing the cuts in the fabric between worlds, and Dust was lost into the void between universes through the cracks of these windows. At that time, the mulefa noticed that their trees – which depend on Dust for fertilisation – had started producing fewer seeds. See also The Book of Dust Dæmon (His Dark Materials) Dark matter Consciousness Footnotes References External links Dust and Panpsychism in His Dark Materials by Attic Philosophy on YouTube Fictional materials His Dark Materials