This podcast episode explores the field of psychedelic medicine, with a focus on ketamine and its use in treating depression. Ketamine has been shown to have profound and long-lasting antidepressant effects, challenging the belief that traditional antidepressants take a long time to be effective. It is recommended to use ketamine as a secondary treatment after trying other therapies, and it should be taken alongside traditional antidepressants. The podcast also discusses the history of ketamine, its therapeutic use, and its potential effects on cognition. The episode delves into the double-edged nature of technology, the concepts of cooperation and altruism in human behavior, the complexities of human nature shaped by evolution, and the impact of relationships on mental health and finding purpose. It concludes with a discussion of the book "Purpose" and its exploration of the intersection between meaning and scientific understanding.