Aryadeva's Four Hundred Stanzas is a foundational work of Mahayana Buddhist philosophy, and Gyel-tsap's commentary is arguably one of the most important written about it. There are no other English translations of the Four Hundred Stanzas with this commentary in print. Mahayana practitioners, Aryadeva says, must eliminate both obstructions to liberation and obstructions to the perfect knowledge of all phenomena. This requires a powerful understanding of selflessness, and an accumulation of merit resulting from the kind of love, compassion, and altruistic intention cultivated by bodhisattvas. The first half of Aryadeva's work focuses on developing merit, and the second explains that all phenomena are empty of intrinsic existence. Gyel-tsap's commentary on Aryadeva's text takes the form of a lively dialogue.