I thought Mr Pratchett looked increasingly shaky in his recent TV programme and subsequent interviews, lobbying for the legal right to choose the manner of his own death. At the moment, he probably believes that that fateful sunny morning when he'll drink his hemlock lies in a misty, indeterminate future: it always will.
He will, sadly, become too confused to make his big decision, and so will slide into dreaded, vegetative oblivion. This seems the unique fate of Alzheimer sufferers - to go from too soon to too late with no mid-place to call an end.
