Despite its wide currency in modern Taiwan，the term 佛光 as well as the concepts connected therewith in the Buddhist tradition have hardly been subjected to academic endeavour. In order to begin to remedy this situation the present paper draws attention to the depiction of the Buddha's effulgence in the `nidana` of the `Bodhisattvago caropayavisayavikurvitanirdesa`. The relevant prose and verse portions of the three versions translated directly from Indian originals are presented as a critically edited synopsis. On this basis, the Tibetan and Chinese renderings of the key term "to obscure" are analyzed philologically，and it is demonstrated how the knowledge derived from this analysis helps to gain a correct understanding of similar passages in other sutras. This leads to the discussion of one of the similies used to describe the Buddha's spendour--the `vaidurya` jewel. It is shown that the Agamas / `Nikayas` generally employed this simile to express "clarity of vision" in itself，but in some cases it is shifted to indicate the clear visibility of the Buddha instead. It is, of course，in this sense that the `Bodhisattvago caropayavisayavikurvitanirdesa` makes use of it. The direct source of this text，however，and this refers to all similes, not just `vaidurya, ` is not the Agama Literature，but with high probability the `Pratyutpanna-buddha-sammukhavasthita-samadhi- sutra`. Yet the author(s) of the `Bodhisattvago` caropayavisayavikurvitanirdesa` did not slavishly copy their source as the meaning of "clear visibility" is distinctly different--in the `Pratyutpanna-buddha-sammukhavasthita-samadhi-sutra` it refers to a meditative practice，in the `Bodhisattvagocaropayavisayavikurvitanirdesa` it is adduced to underline the Buddha's grandeur.
