Hinduism has layers which date back five thousand years. In every hindu ritual to day, modern hindoo ritual, you'll find a lamp is burning. The first thing you do is light the lamp - it actually represents the ancient vedic fires. Layers and layers come. So you can do an archaeology of religion. If you dig into what is therein living in hinduism, you'll come across layers which date Back 5,000 years.
Swami Sarvapriyananda teaches the Katha Upanishad, which is one of the most popular Upanishads. The scripture concerns the story of a young man who goes to the house of death to find out what happens after death. The reply describes the nature of reality and the meaning of life.