瑜伽論記 8.319

8.319

三藏云：又此種姓未習成果說名為細者，謂未習種姓果說名為細，若成習種姓果即為麁，所以爾者，發心已去由習種姓故漸增轉明故名為麁。

The Tripiṭaka Master states: Moreover, that this gotra 'is said to be subtle when not yet cultivated into a fruit' means that prior to cultivating the fruit of the gotra, it is spoken of as subtle; if it accomplishes the fruit of the cultivated gotra, it becomes coarse. The reason for this is that from the generation of the aspiration onward, by virtue of the cultivated gotra, it gradually increases and becomes ever clearer, and is therefore called coarse.