Inhalational agents have played a pivotal role in anesthesia history. The first publicly demonstrated anesthetic of the modern era, diethyl ether, was an inhalational anesthetic. The attributes of a good agent, ability to rapidly induce anesthesia, with limited side effects has led research efforts for over a hundred and fifty years. The explosion hazard was largely conquered with the development of the halogenated agents in the 1950s. Rapid emergence, with limited nausea and vomiting continue to drive discovery efforts, yet the 'modern' agents continue to improve upon those in the past. The future holds promise, but perhaps the most interesting contrast over time is the ability to rapidly introduce new agents into practice. From James Young Simpson's dinner table one evening to the operating suite the next day, modern agents take decades from first synthesis to clinical introduction.