When new medications are being tested, researchers have long been aware of the “placebo effect”—that someone’s mental attitude and preconceptions can impact how that person reacts to the drug. Routinely, scientists attempt to distinguish the placebo effect from the effect of the drug’s active ingredients, to determine how well the medicine itself works. But what is the mystery of the placebo effect? Why do our thoughts and ideas affect our healing from physical ailments? In this episode, we examine some of the history—and promising applications—of this effect, sometimes called the “meaning effect”, because a healing response can be activated by how we perceive the meaning of a medical treatment (drug or otherwise).