Psychedelic therapy has shown great promise for treating depression, but it's still unclear why exactly it works. Psychiatrist Charles Raison wants to know if it's the drug or the trip that makes psychedelics so potent. Is it biology or consciousness?

The news about psychedelics tends to focus on clinical trials and lab research. But there’s a long tradition of underground guides working with plant medicines who refer to "unseen beings" and plants as "teachers." Psychologist Rachel Harris talked with many women elders in the psychedelic underground. She calls them "spiritual warriors."