When Maimonides was a child, in the 1100s AD, he studied Jewish religious law in the Cordoba synagogue. When he was a young man, he studied Aristotle and other scientific philosophers at the University of Fez in Morocco. Then when he grew up, Maimonides became a famous doctor, and also a famous rabbi. How could Maimonides combine these two ways of thinking about the world? That’s what he wrote this book about. To show his concern with science, Maimonides wrote this book in Arabic, the language of science, rather than in Hebrew, the language of religion.
Maimonides began by arguing that people should not think of God as being like a man in shape or in appearance. Instead, they should think of God as more of an idea, with no specific shape or form. Maimonides went over all the places in the Bible where God seems to be shaped like a man. He suggested other meanings for those words.
Then Maimonides described how he thought the universe was put together. He mixed Jewish ideas with Aristotle’s ideas and some ideas from early Christian writers as well. Maimonides knew that the Earth was a sphere. But, like many astronomers in the 1100s AD, he thought that the Earth was in the center of the Universe and the sun and stars all revolved around the Earth in heavenly spheres. (Think of a ball inside a bigger transparent glass ball, inside another bigger glass ball, and so on.) Maimonides thought that these spheres were the same thing as angels. He thought God’s spiritual energy flowed from God to these sphere-angels, and from them to Earth. So God would be the energy that was outside the outermost glass ball.
Finally, Maimonides argued that there were good reasons for all the rules God had told the Jews to follow. That’s the Ten Commandments and the other rules laid out in the Bible. Maimonides thought, like the Buddhists and the Greek philosophers, that people could achieve happiness by using morality to control their desires. (For example, they should follow the Commandment to keep from stealing things). And people could be happy by developing their brains to think more clearly. He thought people should avoid pride and anger, which only led to unhappiness.
Maimonides divided the Commandments into two categories. One is the rational commandments, or common-sense commandments, where anyone who thinks can see that these are good ideas, like not stealing or killing. The other category is revealed commandments. Those are rules where if God hadn’t told people to do those things they couldn’t figure it out through logic. Some examples are the commandments to pray or to observe holidays.
Maimonides thought that the Jewish Law was meant to keep the soul and the body healthy and happy. In some cases, though, he suggested more specific reasons for specific rules. For instance, the rule against mixing wool and linen in your clothing, according to Maimonides, is in there because Greek priests had to wear that mixed clothing. Still, he said, even if the reason for the rule had gone by, you should still live by all the rules of the Law. You should do it just because that was the Law.
Maimonides was not sure what to think about what happened after people died. Sometimes he thought that at the end of the world people would come back to life with both their soul and their body. Other times, he thought just the soul would live after death. And sometimes he thought, like the Roman Neo-Platonists, that after death everybody’s soul blended together into one great Intelligence.