This is what all philosophers do—they sit down in silence and contemplation and think deep questions through to their conclusion. Then they communicate their findings and break through old, preconceived ideas. In this case Descartes, reasons through a lot of questions about the nature of God and the Soul.
How many people can sit still for seven days and meditate like this? It is Descartes who said: “All of humanity's problems stem from man's inability to sit quietly in a room alone.”
He found it was very difficult to keep the old philosophies of life that he had learned, out of his head. He wanted to come up with something original and new. So to really understand Descartes, you would also need to know the philosophers he was trying to erase from his mental patterns, such as Aristotle. But you can still get a lot out of this work and feel the joy of an original mind who dared to be “out there” and continues to add much to this world.