唯識二十論述記 2.91

2.91

述曰：此下正破，釋頌第三句應影無字。且如日輪纔舉，自體放其光已，照觸柱等東邊一面，云何西邊得有影現？此雖理難，義猶未顯有何所以不許有影。

Commentary: Here below is the actual refutation, explaining the words "there should be no shadow" in the third line of the verse. Take for instance when the solar orb has just arisen: after its body emits its light and shines touching one side, the east side, of a pillar or the like, how could a shadow appear on the west side? Although this is a dialectical objection, the reason why a shadow is not admitted has not yet been clarified.