I created a new phrase and asked ChatGPT what it meant. I’m rather pleased with the definition it gave:

“Vertical introspection” refers to a type of introspection that involves delving deeper into one’s thoughts and feelings, often with the goal of gaining a greater understanding of oneself or one’s place in the world. This type of introspection involves exploring the underlying beliefs, values, and motivations that drive one’s actions and decisions. It can be contrasted with “horizontal introspection,” which focuses on the surface-level aspects of one’s thoughts and experiences, such as emotions or physical sensations. Vertical introspection requires a willingness to be vulnerable and to confront uncomfortable truths about oneself, but it will ultimately lead to greater self-awareness and personal growth.