I think you misunderstood what he is saying (or maybe he wasn&#x27;t clear enough): in the first paragraph he says that code decays when it is &quot;changed&quot;, meaning when the codebase is enlarged, grown, more functionality added. On the second, when he talks about interventions, he&#x27;s not refering to the same kind of changes, but to &quot;code maintainence&quot;, which is a distinct and different kind of effort, the one that prevents the decay. For instance, from his point of view, a unit test  is not a change to the codebase, but an intervention. Therefore, the codebase organism enlarges and rots with more code added, and bug fixing, test, refactors, etc, are the efforts needed not to rot. (Conclusion: the analogy is not the culprit :)