The Nirvana Element means the Cessation Element or Unconditioned Element. Lord Buddha’s greatest discovery was that “the Unconditioned exists.” This is the Third Noble Truth, the Supra-mundane Truth that the Cessation of Suffering is possible. It is explained in the Saddhammapakasini as follows:
Cessation has the one direct meaning of being the Unconditioned Element, but also has the two indirect meanings of being with Five Aggregates or without the Five Aggregates, and then the three meanings of quieting the three realms, the four meanings of attaining the Four Paths, the five meanings of quieting the five delights, and the six meanings of extinguishing the six roots of craving.
(KhA. 1/215).
The Truth of the Cessation of Suffering (Nirodhasacca) has two important meanings:
Meaning 1: The Truth of the Cessation of Suffering is the unconditioned element. This refers to the Nirvana Elements in the ultimate sense that the Perfect Ones or Arahants attain. The unconditioned element is not subject to causes and conditions. It has the characteristics of the unconditioned. Arising does not occur, passing away does not occur and while standing, change does not occur.
Meaning 2: The second aspect is expressed in the indirect meanings of the second, third, fourth, fifth and sixth mentioned above in Saddhammapakasini. The two aspects are Saupadisesa and Anupadisesa: Saupadisesa means having the Five Aggregates (Upadi) remaining and Anupadisesa means having no Five Aggregates (Upadi) remaining. This is the Nirvana Element that Arahants attain. Attaining path, fruit, Nirvana with Upadi remaining is called Saupadisesanibbanadhatu or Nirvana with life remaining and without Upadi remaining is called Anupadisesanibbanadhatu or Nirvana without life remaining.
Upadi here has two meanings: (1) The Five Aggregates that are clung to and possessed by Karma and defilements and (2) defilements of clinging (Upadana). Therefore, Upadi can mean either ignorance, defilements, craving, and clinging or the Five Aggregates.