Full Idea
Reason is tempted to surrender itself to a sceptical hopelessness, which might also be called the euthanasia of pure reason.
Gist of Idea
Scepticism is the euthanasia of pure reason
Source
Immanuel Kant (Critique of Pure Reason [1781], B434/A407)
Book Reference
Kant,Immanuel: 'Critique of Pure Reason', ed/tr. Guyer,P /Wood,A W [CUO 1998], p.460
A Reaction
Colin McGinn's 'mysterian' pessimism about the mind-body problem comes to mind!