SN 22.62: What is meant by "scope of language"? What is the message of this sutta?


  At Sāvatthī.
  
  “Mendicants, there are these three scopes of language, terminology,
  and descriptions. They’re uncorrupted, as they have been since the
  beginning. They’re not being corrupted now, nor will they be. Sensible
  ascetics and brahmins don’t look down on them. What three? When form
  has passed, ceased, and perished, its designation, label, and
  description is ‘was’. It’s not ‘is’ or ‘will be’.
  
  When feeling …
  
  perception … choices …
  
  consciousness has passed, ceased, and perished, its designation,
  label, and description is ‘was’. It’s not ‘is’ or ‘will be’.
  
  When form is not yet born, and has not yet appeared, its designation,
  label, and description is ‘will be’. It’s not ‘is’ or ‘was’.
  
  When feeling …
  
  perception … choices …
  
  consciousness is not yet born, and has not yet appeared, its
  designation, label, and description is ‘will be’. It’s not ‘is’ or
  ‘was’.
  
  When form has been born, and has appeared, its designation, label, and
  description is ‘is’. It’s not ‘was’ or ‘will be’.
  
  When feeling …
  
  perception … choices …
  
  consciousness has been born, and has appeared, its designation, label,
  and description is ‘is’. It’s not ‘was’ or ‘will be’.
  
  These are the three scopes of language, terminology, and descriptions.
  They’re uncorrupted, as they have been since the beginning. They’re
  not being corrupted now, nor will they be. Sensible ascetics and
  brahmins don’t look down on them. Even those wanderers of the past,
  Vassa and Bhañña of Ukkalā, who taught the doctrines of no-cause,
  inaction, and nihilism, didn’t imagine that these three scopes of
  language should be criticized or rejected. Why is that? For fear of
  being blamed, criticized, and faulted.”
Clearly the past, present and future (was, is, will be) are all evident and incontestible (i.e., uncorrupted and without defilements). Therefore, this sutta implies that the corruption and defilements arise taking the past, present and future as other than what they are. Indeed, suffering arises when we take the past as the present (remorse or sadness). Or suffering arises when we take the past as the future (craving or aversion). Or suffering arises when we take the past or future as the present (delusion). Mixing up past, present and future is suffering.

Yet if one directly knows what was, is and will be:


  He directly knows water … fire … air … creatures … gods … the Creator … Brahmā … the gods of streaming radiance … the gods replete with glory … the gods of abundant fruit … the Overlord … the dimension of infinite space … the dimension of infinite consciousness … the dimension of nothingness … the dimension of neither perception nor non-perception … the seen … the heard … the thought … the known … oneness … diversity … all … He directly knows extinguishment as extinguishment. But he doesn’t identify with extinguishment, he doesn’t identify regarding extinguishment, he doesn’t identify as extinguishment, he doesn’t identify that ‘extinguishment is mine’, he doesn’t take pleasure in extinguishment. Why is that? Because he has understood that relishing is the root of suffering, and that rebirth comes from continued existence; whoever has come to be gets old and dies. That’s why the Realized One—with the ending, fading away, cessation, giving up, and letting go of all cravings—has awakened to the supreme perfect Awakening, I say 
  --MN1