Deuteronomy is the final book of Moses. There were three period of Moses’ life. The first period was when he was living with the Egyptians and went to visit his people. He saw how harshly they were treated and even murdered an Egyptian that was beating one of his people (the Hebrews). The second period began when he fled to Midian after murdering the Egyptian, and the third period began when he was 80 years old, made his demands on Pharaoh an led the Hebrew out of Egypt.
To read where Jesus quoted the parts of the book of Deuteronomy was amazing to learn.