成唯識論述記 1.449

1.449

述曰：自下第三，更難三德，一一應然。謂此三事，一應能成諸法大等，何假須三；具三相故；如三事合。量云：薩埵一法，應成大等；具三相故；如答摩等合時。若言緣闕一不成者，何所闕少而待三耶？若言要由三，三相合能成大等，故一本事不能成大等。

The Commentary states: From here down is the third [challenge], further challenging the three guṇas that each on its own should be able [to produce effects]. That is, one of these three things should be able to produce the various phenomena such as mahat; what need is there to rely on three? Because it possesses the three marks; like the combination of the three things. The syllogism runs: The single factor sattva should produce mahat and so forth; because it possesses the three marks; like when it combines with tamas and the other. If you say that it fails to produce them because conditions are lacking, what is lacking that it must await the three? If you say that necessarily only through the combination of the three, each having three marks, can mahat and so forth be produced, therefore a single original thing cannot produce mahat and so forth—