R.I.P. - and more

Roger Lloyd-Pack - who brought us the sublime character of Trigger in "Only Fools and Horses".  He may have gone, but Trigger will always be with us, thanks to the nostalgia channels.  One of Trigger's famous boasts (he was a roadsweeper) is that he had used the same broom for 20 years - "it's had 17 new heads and 14 new handles". Which isn't as daft as you might think - some 2,000 years ago the philosopher Plutarch was discussing whether a ship which over the years had had, one by one, every bit of its parts replaced, remained the same ship.  The (very philosophical) question of course is what do we mean or understand by "the same"? As an extreme example, consider a river.  Is it the same river today as yesterday? The water's different.  Hmmm.