大乘義章 1.40

1.40

問曰：因緣是虛妄法，云何能與菩提作因？然彼生死十二因緣起，由妄情託真如立，故經說言「十二因緣皆依真實第一義心」。就妄論之，雖是虛搆，據真緣攝，斯無不實。窮緣悟實，便成大覺，是故因緣能為佛因。故經說言「因者所謂十二因緣」也。

Question: Dependent origination is an unreal dharma; how can it act as a cause for bodhi? [Answer:] Now, the arising of those twelve links of dependent origination in saṃsāra is established due to deluded feelings relying on tathatā. Hence the sūtra says: 'The twelve links of dependent origination all rely on the true mind of ultimate truth.' Discussing them in terms of delusion, they are indeed false fabrications; yet based on the true gathering conditions, none of this is not real. When one penetrates conditions and awakens to reality, one then accomplishes great awakening; therefore, dependent origination can serve as the cause for Buddhahood. Hence the sūtra says: 'The cause is the so-called twelve links of dependent origination.'