大般涅槃經義記 9.100

9.100

次就中人釋答其難。釋意如何？向前問言：眾生有性，無有能遮不得菩提，不須修道。今明佛性眾生未得，故須修道。文中有三：一約空喻明其理性，「非內非外非因果性」是其理也。性非內故假修方得，性非外故修者必得。二約財喻，明其果性非彼非此。性非此故假修方得，性非彼故修者必得。三約業喻，明其因性非內非外、非有無等，義意同前。

Next, regarding the middling person, it explains and answers their objection. What is the intent of the explanation? The earlier question said: Sentient beings possess the nature, and there is nothing capable of preventing them from attaining bodhi, so they do not need to cultivate the path. Now it explains that sentient beings have not yet attained the buddha-nature, and therefore they must cultivate the path. In the text there are three parts: 1. Based on the analogy of space, it explains the nature of principle: "it is neither internal nor external, nor the nature of cause and fruit" is this principle. Because the nature is not internal, it is attained only by relying on cultivation; because the nature is not external, those who cultivate will inevitably attain it. 2. Based on the analogy of treasure, it explains that the nature of the fruit is neither that nor this. Because the nature is not this, it is attained only by relying on cultivation; because the nature is not that, those who cultivate will inevitably attain it. 3. Based on the analogy of karma, it explains that the causal nature is neither internal nor external, neither existent nor non-existent, and so forth; the meaning and intent are the same as before.