The incurability of his optimism.    From Wordnet, Princeton University. 

Adjective : an incurable disease. ,his incurable pessimism.    From Dictionary.com. 

Yet always he found himself harking back to what he sometimes called the "incurability" of life.    From Wordnik.com.  [The Treasure of Heaven A Romance of Riches] Reference

People would gradually give up hope, but there'd be no focal point for despair, no identifiable moment where the incurability of the problem became common knowledge.    From Wordnik.com.  [Mass Sterilization, Reconsidered, Bryan Caplan | EconLog | Library of Economics and Liberty] Reference

Despite its incurability, evidence (814) indicates that the use of dihydroergotoxine mesylate (Hydergine), an ergot derivative, can improve cognitive functioning to some degree in certain patients.    From Wordnik.com.  [The Neuropsychiatric Guide to Modern Everyday Psychiatry] Reference

How many other people battling other diseases will find that, because the numbers don't add up, they won't find out they have a heart condition or prostate cancer before the disease has advanced to incurability.    From Wordnik.com.  [Do risks of routine mammograms really outweigh benefits?] Reference

That we as health-care consumers no longer accept chronicity or incurability, but instead expect medical science to produce solutions to previously insoluble problems, represents a true change in the way of thinking.    From Wordnik.com.  [Global Economic Pressures and the Quest for New Medicines] Reference

Just as the usual statements in regard to the extent of venereal disease have been found untrue or greatly exaggerated, so do the statements regarding the curability or rather incurability of venereal disease need careful revision.    From Wordnik.com.  [Woman Her Sex and Love Life] Reference

Having read the extract from the rant about the 'wicked' Jews and the supposed insight into their incurability in the 'holy koran', it makes one wonder how these leftist idiots can be taken in by our islamist nutters and their innate racism.    From Wordnik.com.  [Giving evidence to the Chilcot inquiry, Tony Blair said: “I...] Reference

Here again the "sad fact of incurability" must be recognized.    From Wordnik.com.  [Friendly Visiting among the Poor A Handbook for Charity Workers] Reference

"One of the cornerstones of the 'watch and wait' argument is the incurability of advanced stage follicular lymphoma," he wrote.    From Wordnik.com.  [Media Newswire] Reference

But weaknesses and malformations, which to-day are attributable to a vicious schoolmaster and a pernicious system, will a century hence be rightly regarded as proofs of innate corruptness and radical incurability.    From Wordnik.com.  [A Voice From the South] Reference

Page 8 of the unfortunate, and every chance for recovery would be given under the guidance of those acquainted with the needs of the case, a safe conduct to health, if possible, and careful protection in the event of incurability.    From Wordnik.com.  [An Appeal for State Care for All the Insane from an Economic Standpoint. The Report of the Chairman of the Section on State Medicine and Medical Jurisprudence Made to the Medical Society of the State of North Carolina, May 28th, 1891] Reference

But soon Madame Caraman found reason to doubt the incurability of her patient -- she noticed that Clary, when leaving her carriage, or performing any other movement of the body, usually painful for chest complaints, never felt pain or the slightest inconvenience.    From Wordnik.com.  [The Son of Monte-Cristo, Volume I] Reference

Such being the facts, one can hardly employ language too importunate, arguments too persuasive, to secure such increased accommodations for the Insane throughout the United States, but especially in those States in which no Hospitals have been established, as shall assure their sufficient care and protection; their remedial treatment so as to procure recovery when recovery is possible; and their safety and guardianship in all cases where the terrible calamity of incurability crowds them forever from all the bland affections, and social enjoyments of domestic and friendly association.    From Wordnik.com.  [Memorial Soliciting a State Hospital for the Protection and Cure of the Insane, Submitted to the General Assembly of North Carolina. November, 1848. [House of Commons Document, No. 2.]] Reference