Good morning. This is the last Brainstorm Health Daily before we break for the holidays. We’ll start up again in the new year.

But before we go, I thought I’d share three bits of wisdom that seem pertinent to the ongoing revolution in healthcare. The first two come from books I’d read this year: one by a gifted young science writer, the second by an oncologist-turned-Pulitzer-Prize-winning-author. The final offering comes not from a book but rather from a conversation I had with a young physician, Raj Panjabi, at the Fortune + Time Global Forum in Rome earlier this month. Panjabi, whom I wrote about here, is an American-trained physician who returned to his native Liberia to help build a rural healthcare system serving the poorest of the poor. That system—essentially, a brigade of local villagers trained as community health workers—helped stop the epidemic of Ebola that raged through West Africa in 2014 and, for a time, threatened the entire world.

Here, some eye-opening passages and what I took away from them:

1. “The microbiome is a not a constant entity. It is a teeming collection of thousands of species, all constantly competing with one another, negotiating with their host, evolving, changing. It wavers and pulses over a 24-hour cycle, so that some species are more common in the day while others rise at night. Your genome is almost certainly the same as it was last year, but your microbiome has shifted since your last meal or sunrise.”—Ed Yong, I Contain Multitudes: The Microbes Within Us and a Grander View of Life

My takeaway: Yong’s writing offers a lyrical reminder of something we ought to keep in our heads as we design next-generation diagnostics and treatments—Biology is dynamic; the human body is an ever-changing, interactive, and renewing system, one in which everything from gene expression to protein signaling is in a constant state of flux. So as much as we have strived for accurate “real-time” diagnostics, we must develop tests that provide context, too. Taking a Polaroid of the body offers us a picture of the most fleeting of moments. We need the equivalent of digital video—a narrative with history.

2. “It is nonsense to speak about ‘nature’ or ‘nurture’ in absolutes or abstracts. Whether nature—i.e., the gene—or nurture—i.e., the environment—dominates in the development of a feature or function depends, acutely, on the individual feature and the context. The SRY gene determines sexual anatomy and physiology in a strikingly autonomous manner; it is all nature. Gender identity, sexual preference, and the choice of sexual roles are determined by the intersections of genes and environments—i.e., nature plus nurture.”—Siddhartha Mukherjee, The Gene: An Intimate History

My takeaway: As we think about improving our healthcare interventions, we have to break free from the false notion that discrete “biological mechanisms” (a mutation in X gene, for example) “cause” disease. While that is occasionally true, in the overwhelming share of cases, disease causation is far more complex—involving a large number of factors that interact with and influence one another over months, years, and often decades. We are used to quick technological fixes—click thumbs down and a Pandora song is summarily dismissed. For the next generation of health interventions to be effective, we must move beyond that one-button mentality.

3. “The hotspots of inequality correlate very closely with the hotspots of disease. That’s true in Ebola: A two-year boy died in a rainforest community hours away from the nearest clinic. It’s true of recent elections. Diabetes and obesity rates correlated more with the outcome of the U.S. election than even typical political indicators did in rural America—Raj Panjabi, at Fortune + Time Global Forum, Dec. 2.

My takeaway: Amid the flurry of excitement over new technologies and ventures, we have to keep our eyes on the mission. Today, more than a billion people on the planet have essentially no access to healthcare because they live in rural or remote areas, too far from the nearest clinic. While great progress has been made in global health—child mortality overall has been cut by half since 1990—large portions of the earth’s population have been left behind. Our modern healthcare revolution has to keep them foremost in mind.

Says Panjabi, recounting a scene that is still played out today across much of sub-Saharan Africa: “When a two-year old gets sick in the village, a mom has to take him to a riverbed, get in a canoe, paddle to the other side, and then walk for two days just to get a diagnosis. How do you solve that?”