十不二門指要鈔 2.33

2.33

First, explaining that the principle of beginning and end is one. 'Sentient beings', broadly speaking, applies to both cause and effect, because the Buddha is called the unsurpassed sentient being; narrowly speaking, it is restricted, because sentient beings are established in contrast to the Buddha. Although sentient beings pertain to the cause, they further encompass everything. Taking solely the mind-cause as the essence of contemplation here, this essence inherently possesses the three tracks and is the nature of the effect; therefore it is named cause. When this nature is manifest, it is called the three nirvāṇas; the essence of the three dharmas is eternal, and the principle of beginning and end is one.