Introduction
According to Mahayana, Buddhas can manifest simultaneously in innumerable physical forms to help innumerable limited beings throughout all universes. When these emanations are in the form of Sambhogakaya (longs-sku, a Corpus of Bodies of Full Use) or Supreme Nirmanakaya (mchog-gi sprul-sku, a Corpus of Supreme Emanation Bodies), they are complete with 112 physical faculties, namely the 32 excellent signs (mtshan bzang-po gsum-cu rtsa-gnyis, 32 major marks) and 80 exemplary features (dpe-byad brgyad-cu, 80 minor marks). Each of these signs and features has a corresponding cause in terms of constructive actions practiced in previous lives. The excellent signs are the indications of a great person (skyes-bu chen-po, Skt. mahāpuruṣa), while the exemplary features reveal inner qualities and serve to make a positive impression on the mental continuum of others. If we are aware of the causes of each of these features, then these physical faculties will show us very clearly the safe direction (refuge) to take.

Wheel-wielding emperors (’khor-los sgyur-ba’i rgyal-po, chakravartin emperors) are also considered “great persons” and their bodies also display the 32 excellent signs and eighty exemplary features. According to the abhidharma tradition of topics of special knowledge, these emperors appear during a world eon only when the human lifespan is decreasing from a countless number of years to 80,000 years. They wield a gold, silver, copper, or iron wheel of authority, depending on whether they rule over four, three, two, or one island-continent of a world-system.
Although wheel-wielding emperors share the same bodily features of a Sambhogakaya and Supreme Nirmanakaya Buddha, they lack the other qualities of a Buddha and thus are not fitting objects indicating safe direction. For example, a wheel-wielding emperor cannot emanate innumerable bodies simultaneously throughout all universes in order to benefit all limited beings. Further, according to Mahayana, a Buddha’s enlightening body pervades all Buddha-fields (sangs-rgyas-kyi zhing) and all Buddha-fields appear in every pore of a Buddha’s enlightening body. Wheel-wielding emperors lack such inconceivable physical qualities.
According to the anuttarayoga tantra explanations, since the mind of a Buddha is omniscient and therefore pervades all the countless universes and all knowable things within them, the enlightening body of a Buddha likewise pervades all the countless universes. This is because the enlightening mind of a Buddha is a clear-light mind, the subtlest level of mind; while a Buddha’s enlightening body is the subtlest energy-wind that is inseparable from that clear-light mind. Thus, wherever a Buddha’s clear-light mind pervades, a Buddha’s Corpus of Enlightening Bodies (gzugs-sku, Skt. rūpakāya, Form Bodies) also pervades. Wheel-wielding emperors certainly lack this quality of an all-pervading body.