Yogācārabhūmi-śāstra, Volume 10 (Twelve Links of Dependent Origination)

(24) Original text: 问。是诸有支。几与道支。所摄正见。为胜障碍。答。无明及彼所起意行。若有一分。能为胜障。如于正见。如是于正思惟。及正精进亦尔。若正语正业正命。以身行语行。及有一分。为胜障碍。若正命正定。以余有支。为胜障碍应知。 

Explanation: Question: Among the twelve links of existence, how many links constitute a superior obstacle to right view, which is included among the links of the Eightfold Noble Path? Answer: Ignorance and the mental formations (volitional formations of mind) arising from it — if even one portion of them is present, they can constitute a superior obstacle. How much more so when there are many portions — they are even more of an obstacle. Ignorance and the formations not only obstruct right view; likewise, they also obstruct right thought and right effort. As for the bodily formations and verbal formations of the link of formations, if even one portion is present, they become a superior obstacle to the superior dharmas of right speech, right action, and right livelihood. The remaining links, such as consciousness, contact, feeling, perception, and grasping, if even one portion is present, will become a superior obstacle to the superior dharmas of right livelihood and right concentration. 

The twelve links of existence are an obstacle to the correct practice of the Eightfold Noble Path, and they are also an obstacle to the practice of the other factors of the path. Likewise, they are an obstacle to the practice of the Four Noble Truths of suffering, its origin, its cessation, and the path. Therefore, no matter what dharma one cultivates, ignorance is always an obstacle, and the common goal of cultivating all dharmas is to break through the obstacle of ignorance. 

Original text: 问。是诸有支。几唯杂染品。几通杂染清净品。答。四唯杂染品。余通杂染清净品。问。云何生支通二品耶。答。若生恶趣及有难处。唯是杂染品。若生人天诸无难处。此通染净品。当知余支。随其所应。皆通二品。 

Explanation: Question: Among these links of existence, how many links pertain only to the defiled category? And how many links pertain both to the defiled and to the pure categories? Answer: Four links pertain only to the defiled category, while the rest pertain both to the defiled and to the pure categories. Question: Why does the link of birth pertain to both the defiled and pure categories? Answer: If one is born into the three evil destinies or into places beset by calamities, birth pertains only to the defiled category; if one is born among humans or devas in places free of calamities, birth pertains to both the defiled and pure categories. From this it can be known that the remaining links, in accordance with the dharmas they correspond to, all pertain to both the defiled and pure categories.