I make the joke about the three paragraphs because many millions of pages have been written, and similar numbers of "subjects" studied on this still topic. And, while much meaningful information has been discovered, and much solace is to be found in the art created by those suffering, depression for me remains elusive.
As a medical psychotherapist with over two decades of experience in intensive mental health care, I try to walk the line every day with my patients. I use "proven" therapies such as cognitive behavioural therapy and mindfulness-based practices; we explore a trauma-based perspectives; we work through writing and other art forms for healing; and, we work on self-care. I also prescribe medication for some, and more often that not, while medication is never the "answer," it often lifts the veil of depression enough for psychotherapeutic endeavours to be more successful.
Patients ask me, "What is it, depression?" I answer ever in a blur of explanations involving physiology, neuroscience, family history, trauma, triggers, and so on. The truth, I admit every time, is that we really don't know. We just don't know. We know enough to often be able to be of some help, but we don't really know.