Thomas Brooks preaches on the name 'El-Shaddai,' which means 'God Almighty' as stated in Genesis 35:11. He emphasizes that God embodies omnipotence and sufficiency, being an all-sufficient, self-sufficient, and independent good. Brooks highlights that God is the absolute and original good, the universal source of satisfaction, and perfectly suitable for our souls. This sermon encourages believers to recognize and rely on God's sufficiency in all aspects of life.