The expression “Innate Luminousism” is a neologism that I am coining here to express the Buddhist philosophical idea that the nature of mind is luminous. Readers who know this Buddhist concept well may, for the time being, withhold their enlightening lecture on the topic, because this is not my motive for addressing the issue here. My interest here is how precisely does Rong-zom-pa, an eleventh-century Tibetan scholar, understand this concept. Those readers who can provide insights on Rong-zom-pa’s understanding of the concept based on concrete, explicit, and unambiguous textual sources are, of course, welcome to comment. I shall propose my own understanding of how he understands the concept. As far as I am concerned, the most fundamental understanding of the statement that the nature of mind is by nature luminous is that mind in its elemental state is untainted and ”untaintable,” unpolluted and ”unpollutable.” All stains, pollutions, or contaminations are thus adventitious and are foreign to the actual pure nature of the mind. It is because of this quality of the mind, that is, the natural purity of the mind and its quality of pollutability and purifiability, that purification and pollution are at all possible. This seems to be the very crux of Buddhist soteriological mechanism. The pure nature of mind at its elemental level or state may be compared to water in its molecular state and level (i.e. H20). The question is if mind can be reduced to non-mind, that is, to the extent that it loses the identity and quality of mind. I have a feeling that some Buddhist philosophers believed that it is possible. This would be like splitting hydrogen and oxygen present in H20, thereby losing the identity and quality of water. But what about Rong-zom-pa’s understanding of the statement that mind is by nature luminous? If to carefully examine the way he explains the concept of rang bzhin gyis ’od gsal ba’i rnam par thar pa (obviously according to the special soteriology of what he calls “special Mahāyāna”), it seems to be clear that rang bzhin gyis ’od gsal ba’i rnam par thar pa is the realization that both pollutants and purifiers are not substantially existent. For him, therefore, mind and its pollutants and purifiers are not only like water, its pollutants and purifiers but more so like mirage-water and its pollutants and purifiers. Apparent mind may appear to polluted and purified, but like mirage-water, there has never been mind, nor its pollution, nor its purification, even when the apparent mind appears to be polluted or purified. So it seems that for Rong-zom-pa, it is not so much because of the natural purity of the actual mind and its quality of pollutability and purifiability that one speaks of the luminosity of the mind, but rather that one speaks of the natural luminosity of the mind because of the innate non-substantiality of the apparent mind and its immaculate nature which is always and essentially devoid of pollutants and purifiers. Perhaps one might say that for Rong-zom-pa only that quality or reality that transcends the duality such as of pollution and purification, day and light, light and darkness, and so forth, can be called naturally luminous. My understanding might become a little more plausible if we consider the expression “the nature of space is luminous” that he, if I am not mistaken, also employs. That is, for him, we cannot say that the nature of space is luminous only when the sun shines or only when there is light. Luminosity in its ultimate sense should be, I think according to him, that quality or reality of the space that is inherently, intrinsically, and primordially pure (i.e. empty) of anything that does not belong to the quality of space. For the time being, I cannot think of a better explanation of his understanding of innate luminosity. There are many shades and levels of understanding the concept of luminosity, but the two that I alluded here seem to be crucial or significant.