Insertion is the procedure by which a soul is implanted into the body of a new host. It is considered to be a very simple procedure which "any soul on the street could perform in an emergency". Typically, insertions result in a loss of the host's sentience, with an anomaly being humans with knowledge of what is coming. As a rule, insertions are only performed by Healers, the soul equivalent of a medical professional and intellects, these are the cleverest souls (cleverer than researchers) who have more than five callings one of which is healer. But still it is unknown where the actual insertion is medical equipment came from.