“Simplex sigillum veri - The great seal of truth is simplicity.” Hailed as a Dutch Hippocrates, Herman Boerhaave's motto is very similar to a slogan that you still often hear in medicine: "When you hear hooves, think of horses, not zebras.” Often, the simplest conclusion to a medical problem turns out to be the correct one. The reason why we can now make so many medical diagnoses is thanks to the doctors of the past who carried out research on both living people and corpses. Voluntarily and involuntarily. Ethically and unethically. Boerhaave was one of these doctors, and the research he carried out in Leiden has had a huge impact on the world. Today, you can immerse yourself in his life and research — wander through the Leiden museum named after him!