Some people believe that mankind is imperfectible.    From LearnThat.org. 

The final consumer good is beauty in our surroundings, and beauty is both individual and imperfectible.    From Wordnik.com.  [A Kingdom for a Frame, Bryan Caplan | EconLog | Library of Economics and Liberty] Reference

Man is an imperfectible animal, and because he is, we can't eliminate hate-we can't eliminate brutality-we can't eliminate unreason.    From Wordnik.com.  [Canadian and American Relations] Reference

Its opening sentence, "Life is difficult", introduced a tome which argued, uncontentiously and sensibly, that human experience was trying and imperfectible, and that only self-discipline, delaying gratification, acceptance that one's actions have consequences, and a determined attempt at spiritual growth could make sense of it.    From Wordnik.com.  [BatesLine: October 2005 Archives] Reference

Human nature being the imperfectible thing it is, he thought, the French would more than likely "run to anarchy.".    From Wordnik.com.  [City Journal] Reference

Against this, her vocals stood even more intensely as the pure residue, the hauntology in the machine, the tragedy of the soul imperfectible by science.    From Wordnik.com.  [Drowned In Sound // Feed] Reference

Augustinianism), which, by definition, asserted that humans were fallen, imperfect, and imperfectible by their own devices.    From Wordnik.com.  [Dad29] Reference