sentences:  In later stanzas, he describes the birth of the universe, covers Newton's laws and explains gravity.He interweaves such physics and mathematics framed as poetry with theological and philosophical musings about the purpose of the universe, the nature of good and evil, and God's intent.Towards the end of his teaching career, Björn wrote down the mathematics he would have liked to teach in the "Tölvísi", a mathematical textbook unprecedented in Iceland, both in its breadth and depth, but also in the rigor of its proofs.