tility of the 4-d way of thinking 
seems to be lost, since these 'objects' are no longer 4-dimensional 
entities, and the ways they might be related to 4-d histories are 
much more complicated than the ways that 3-d objects might be related 
to their spatial extensions. For example, consider a 'thing' 
consisting of the top of my head one day and the bottom of my feet 
the next day and a smooth morphing between these, ie a kind of 
slow-moving surface which takes 24 hours to scan me from head to 
foot. It's