Khunrath is credited with having created the first alethiometer. He discovered that a needle made from an alloy of two particular rare metals would point towards the truth. He first suspended it over a zodiac chart, noticing that he could influence its movement by asking questions. Later, he used the memory-theatre idea developed by Giulio Camillo and Giordano Bruno to provide himself with a wider array of images. Khunrath found that the meanings for the symbols somehow already existed, and that he was discovering rather than inventing them.
In 1612, Emperor Rudolf II died and, with it, Khurath's research. Emperor Frederick opposed what he deemed occult experimentation, and at some point during Emperor Frederick's reign, Khunrath was burnt at the stake for heresy.