Hippocrates (460–370 BCE), the Greek physician often hailed as the “father of Western medicine,” is best known for his declaration primum non nocere, or, “First, do no harm”. Whether he uttered those exact words is uncertain, but their spirit has anchored medical ethics through the centuries. Also attributed to him, ‘All disease begins in the gut,’ feels especially pertinent today. Again, the exact phrase may be apocryphal, but the underlying insight lives in his teachings. As modern science expands our understanding of how trillions of microbes in our intestines influence our immunity, metabolism, mood, and aging, I see Hippocrates’ intuition in a new and more profound light. Revisiting that ancient medical tradition helps us think about health and longevity in a more integrative and holistic way, ideally helping us to enhance both.