Solving the oxymoron of nibbāna? How does one remain dedicated to the pursuit of nibbāna, when one has seen clearly that ultimately there is no separate nibbāna. What does one aspire towards now?

Prajñāpāramitā Hṛdaya sūtra: «There is no suffering, no cause of suffering, no end to suffering, no path to follow» 


  Where beauty is, then there is ugliness; where right is, also there is wrong.
  Knowledge and ignorance are interdependent; delusion and enlightenment condition each other.
  Since olden times it has been so. How could it be otherwise now?
  Wanting to get rid of one and grab the other is merely realizing a scene of stupidity.
  Even if you speak of the wonder of it all,
  how do you deal with each thing changing?  
  
  ................................................................................................~Ryokan
When the Heart Sutra says "There is no suffering, no cause of suffering, no end to suffering, no path to follow" it isn't saying that none of these things exist. What it means is that none of these things exist in terms of 'Svabhava' which means something like 'intrinsic existence' or 'self nature' or 'essence'. In terms of 'Svabhava' none of these things exist, but in terms of the experience of these things and in terms of their actual features and characteristics, they do exist.

And I think that the quote by Ryokan means that opposites are concepts which are relative and exist as abstract concepts which are imputed onto experience. It is absolutely true that the abstracted concept of Nibbana and the abstracted concept of conditioned existence relatively depend on each other as part of a dualistic pair, but that doesn't mean that the experiences and properties to which these concepts refer are themselves interdependent.