The famous Ganapati Atharvasirsa Upanisad reveals the true nature of everyone's favourite - Lord Ganapati. He is the infinite Truth (Brahman) and the Self of all (Atman).
It also shows how the divine form of Ganapati manifests from the bija mantra 'om gam'. It concludes with enumerating different ways of worshiping Ganapati and the results attained through them (phala sruti).
Swami Tejomayananda's commentary is easy to read, yet deep in meaning. It inspires the reader to become a life-long devotee of God.