If I tell you what I know, why have I lost nothing?

To live is to burn. A neuron firing, a cell dividing, a thought taking shape — each costs energy. The body is, among other things, a furnace, and a recent essay in Nature argues persuasively that biomedicine has been too willing to forget this. Picard and Kempes ask researchers to look at health and disease energetically, from the first principles of physics. They are right. But they are not complete.

There is a paradox inside the energetic view that the essay nearly names and does not pursue. The act of acquiring energy can cost more than it yields. A body that eats to feel alive sometimes drains itself in the eating. Restraint, in such cases, is not the absence of having — it is a form of having. The fast can hold what the feast spends. This much remains inside the frame. What lies outside it is harder to see.

When I tell you something I know, I do not lose the knowing. Neurons fire, air vibrates, photons travel — the signal between us costs energy. But the content of the signal is not depleted by its transmission. You now know. I still know. The world contains one more instance of the knowing than it did a moment ago, and nothing has been subtracted to make this so.

This is not a violation of physics. Landauer's principle still holds: information processing has thermodynamic floors. The substrate is bound. But the meaning carried by the substrate follows a different logic. Energy is conserved. Meaning is not. The same caloric cost writes 道 and 错. Energy explains that the writing happened. It does not explain what was said.

So when Picard and Kempes urge biomedicine toward first principles, they are right about the substrate and silent about the rest. A living body is not only an energetic system. It is also a meaning-bearing one — a transmitter, a receiver, a node in a network of signals whose content does not deplete by traveling. To reduce a being to its energy is to describe the channel and miss the message.

Perhaps this is what it means to be alive in a way mere combustion is not: to participate in transmissions that do not obey conservation. To pass on what cannot be subtracted. The fire consumes the wood. The teaching does not consume the teacher. What flows through us is energy. What flows from us is something else.

Pass on what cannot be subtracted. The world has room for it.