When we refer to the Four Common Preliminaries we can also call them the Four Thoughts that Turn the Mind from Samsara. The first one is cultivating an appreciation for our precious human birth, the second concerns impermanence and mortality, the third describes karma and its consequences, and the fourth explores the shortcomings of samsara. All of the different schools and lineages of Tibetan Buddhism strongly prioritise contemplating each of these four thoughts. In the Gelug tradition, for example, Tsongkhapa’s treatise, The Path to Enlightenment, contains a very detailed description of practice methods for cultivating renunciation. In the Kagyu lineage, Gampopa also composed treatises which clarify how one should go about these practices. In the Nyingma tradition we have the introduction to the Dzogchen preliminaries, The Words of My Perfect Teacher, in which the preliminary practices are also described in great detail. The Sakya lineage and the Jonang lineage also have their own texts dealing specifically with concrete practices for the four preliminaries. In brief, the Tibetan tradition in its entirety regards the preliminary practices as fundamental.
Depicted from "Guide to the Four Preliminary Practices 1 - Part 38" April, 2015, Vancouver, Canada