at symbols, and the reader has to hold the level of meaning for each symbol in their head. A fourth lever, made of an alloy sensitive to Dust, swings around, stopping on different symbols to give an answer, with the number of times it stops at a given symbol indicating the level of meaning intended. In La Belle Sauvage, it is said that no more alethiometers can be built, as their construction depends on a rare metal being subjected to special treatment, knowledge of which has been lost. Oxford has an alethiometer in its library, which is read by Hannah Relf, various other universities have one, and one is missing. After the Magisterium attempts to steal one, a secret society opposed to their actions is able to obtain it, and give it to Relf to use on their behalf. The missing alethiometer is found by Malcolm Polstead in the pack of Gerard Bonneville, and given to the Master of Jordan College, for safekeeping. In Northern Lights, it is this alethiometer which is given by the Master to Lyra, who is able to read it intuitively. At that point in the story, only two other alethiometers are known to survive. History within the books Within the books, Dust came into existence when consciousness did; it was created by consciousness, as well as being conscious. Occasionally, Dust condensed into Angels; the first of these was called The Authority, who told all the angels that subsequently condensed that he was the creator of the multiverse. In the trilogy, Angels are formed from condensing Dust. These angels only appear as winged humans because that is what is expected of them; in reality, they have more complex shapes, similar to "architecture". About 33,000 years prior to the time of the books, Dust had induced changes in sapient species, including humans and mulefa, to allow them to interact better, conferring more consciousness. For the mulefa, this was the start of their oral history and memory as a species. When asked directly, Dust states that this was done by rebel angels for vengeance over the war in heaven.{{efn|name=vengeance|The dust explains its intervention in the evolution of sentient creatures to Mary Malone: And did you intervene in human evolution? . Why? .Vengeance for – oh! Rebel angels! After the war in Heaven – Satan and the Garden of Eden. — The Subtle Knife}} 300 years before the start