The Romans were the first to turn mustard seeds into the everyday condiment we know today. They ground the seeds and mixed them with 'must' (unfermented grape juice), which is where the name 'mustard' (mustum ardens, or 'burning must') comes from. Mustard is chemically fascinating: the seeds themselves aren't spicy. The 'heat' only develops when the seeds are crushed and mixed with liquid, triggering an enzyme reaction that produces allyl isothiocyanate. Interestingly, different liquids change the heat level—cold water creates the most pungent mustard, while vinegar or hot water partially deactivates the enzyme, resulting in a milder flavor.