Listen to the person in front of you; they are usually telling you the answer.
Osler's teaching from around 1904. It survives because it is empirically sound: history-taking still yields more diagnostic information than any single test.
In practice
- A doctor who asks when the pain started and what makes it worse has the diagnosis before the blood results arrive.
- A support engineer who lets the customer describe what they were doing solves faster than one who goes straight to the logs.