To realise the beginningless purity and perfection of all reality as an indivisible unity of Voidness and appearance is to realise Dzogchen - the Great Completeness. The lineage of this Mahayana system of meditation traces from Shakyamuni Buddha and was taken from India to Tibet by such masters as Guru Rinpoche Padmasambhava and Vimalamitra. It has been transmitted mainly through the Nyingma Tradition of Tibetan Buddhism and its oral teachings preserved unbroken until the present day.
This text by Longchen Rabjampa also known as Longchenpa (1303-1363) - one of the greatest codifiers of the Dzogchen teachings as witnessed by his trilogy Kindly Bent to Ease Us , is an exposition on the "Four Themes of Gampopa" - the author of The Jewel Ornament of Liberation. It includes a survey of the nine vehicles to Enlightenment as travelled progressively through the sutra, tantra and Dzogchen modes of approach, as well as a description of the goal. This it does primarily by expounding the techniques utilised at each of these stages for removing confusion about the abiding nature of reality.
The commentary of this text was provided orally by His Holiness Dudjom Rinpoche - the present head of the Nyingma Tradition, and supplemented by Beru Khyentze Rinpoche.
— From the back cover.