H alloween is not exactly a typical holiday. Other holidays, like Christmas and Shavuot, celebrate an event. Halloween celebrates a lot of things, including the lives of people who aren't with us anymore. The history of Halloween is not entirely a clear one. Here's how (we think) it started: Many hundreds of years ago, a people called the Celts lived in Europe and on the British Isles. The Celts believed that the souls of the dead visited Earth on the last day of October. They had a festival in honor of these souls of the dead, and they called it Samhain. In time, the Roman Empire conquered the Celts and took over some of their beliefs as well. This included Samhain. The Romans combined it with their own festivals. And since the Roman Empire spread across a great part of the known world, the idea that the souls of the dead visited Earth on the last day of October spread far and wide. Many ideas from the Roman days still survive in the Unit...