In Philip Pullman's His Dark Materials trilogy of novels, Dust is a mysterious cosmic particle that is integral to the plot. In Northern Lights, Lord Asriel reveals the origins of the term "Dust" to be from a passage from the slightly alternate version of the Bible in Lyra's world: "In the sweat of thy face shalt thou eat bread, till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return" (Genesis 3:19).
Description
Pullman's Dust is a fictional elementary particle that is of fundamental importance within the story. It is invisible to the human eye and cannot be seen without the use of special instruments, such as the amber spyglass which Mary Malone constructs in book three. While humans cannot see Dust unaided, creatures such as the mulefa are able to do so.
Unlike ordinary particles, Dust is conscious. It falls from the sky, is attracted to people, and wears off onto objects made by people. This makes it of great interest to the Church, which believes that it may be the physical manifestation of Original Sin. It is later learned that Dust confers consciousness, knowledge, and wisdom, and that Dust is formed when matter becomes conscious. This allows creatures who are able to see Dust to identify other sentient and intelligent creatures. An example of this is when the mulefa are able to distinguish Mary Malone as an intelligent being, because of the Dust surrounding her.
Dust is also what connects humans to their dæmons. If the bond between a child and their dæmon is severed (as through Intercision), both the child and the dæmon will eventually die. If the separation occurs after Dust has settled on the person (that is, after adolescence), the person becomes a lifeless shell.
It is Dust that provides the answers given by the alethiometer, possibly the I Ching system of divination and also the computer that Dr. Mary Malone creates in order to communicate directly with these particles using consciousness.
Dust has various names in the various worlds within the trilogy. Dust was previously known (in Lyra Belacqua's universe) as 'Rusakov particles' named after their discoverer, Boris Mikhailovitch Rusakov. It is referred to as 'Shadows' by Mary Malone, in our world. Pullman relates Dust to dark matter, and the mulefa 'sraf', when accompanied by a leftward flick of the trunk (or arm for humans).
In Pullman's trilogy, Angels are formed when Dust condenses.