十不二門指要鈔 2.33

2.33

初、明始終理一。眾生一往通於因果，佛名無上眾生故，二往則局，因對佛立生故。生雖在因復通一切，唯取心因是今觀體，體具三軌是果之性，故名為因。此性若顯名三涅槃，三法體常始終理一。

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.