F-06 · The Immune System, Drawn From Memory
The second time you meet a particular germ, you often never know it. The first time you caught a given cold virus — maybe as a small child — you were sick for a week. The next time the same virus tries the same trick, you may feel nothing at all. No fever, no aching, no day in bed. The threat arrives, and something in you answers so quickly and so precisely that the fight is over before it can become an illness you’d notice.
That gap between the first encounter and the second is the most important thing to understand about your immune system. It is not, at its heart, a wall or an army. It is a system that learns — that meets a threat, studies it, and keeps a record. The response you mount the second time is, quite literally, drawn from memory.
