妙法蓮華經玄義 5.120

5.120

若將此麁妙等乘，約五味者，乳教一麁一妙。酪教一麁。生蘇三麁一妙。熟蘇二麁一妙。眾經悉帶縱橫方便，說不縱、不橫之真實，故言為麁。今經正直捨方便，故加之以妙（云云）。

If we correlate these crude and subtle vehicles with the five flavors: the milk teaching has one crude and one subtle; the curd teaching has one crude; the raw ghee teaching has three crude and one subtle; the cooked ghee teaching has two crude and one subtle. Because all the sūtras contain vertical and horizontal expedients when expounding the reality that is neither vertical nor horizontal, they are described as crude. The present sūtra directly discards expedients; therefore, it is termed subtle (and so forth).