1. A slice of cheese between two slices of bread. This is a sandwich. It is a cheese sandwich. 2. A slice of bread between two slices of toast. This is also a sandwich: it clearly has upper and lower bits and also a middle bit. Interestingly, a sandwich of this type was briefly haunted by the ghost of the fourth Earl of Sandwich, which has used its posthumous fame to blag its way into many of the world's best sandwiches. 3. A loaf of sliced bread. You might think that this was a sandwich, containing as it does some stuff (in this case lots of slices of bread) between two slices of bread. But one has to draw the line somewhere. Sandwiches, fundamentally, are not recursive items. A sandwich that contains another sandwich is not a sandwich, it is something entirely other. It is a cube in a land of squares. It may be a truly ecstatic dining experience. But a sandwich it is not. 4. A marshmallow between two biscuits. Here we come to one of the challenges in sandwich philosophy. Is bread required, or is an item having a bread nature sufficient? If so, does the mere act of enclosing another item between two slices of something lend to it a certain breadiness? Any person of a generous nature must surely be convinced of this truth - in which case, such an item is unquestionably a sandwich. 5. A person in between a duvet and a mattress. This is not a sandwich in the classic mold, lacking as it does the fundamental symmetry beloved of sandwich-eaters. It is however arguably an open sandwich with two toppings. This applies unless the person has recently eaten a sandwich, in which case see principle 3. 6. Two slices of delicious hedgehog, enclosing another slice of delicious hedgehog. Following the principles discussed above, this is definitely a sandwich. Furthermore, given that nearly everything is fundamentally still in the same place before and after slicing, I am sure you will agree that a hedgehog is also a sandwich. 7. The Universe. Applying the hedgehog principle more generally, we consider the theoretical case of dividing the Universe into three equal parts, the central one of which we will arbitrarily designate as filling. Using the sandwich normalisation axiom, it can be shown that the enclosing parts in this case have a bread nature. Therefore the Universe is a sandwich. 8. A slice of cheese between two slices of bread. As discussed above, sandwiches are not recursive. However, by applying principle 7 we have shown that the Universe itself is a sandwich. Therefore, nothing within the Universe may be a sandwich. There can be only one and all other sandwiches are a lie. I hope this clarifies matters in the great sandwich discussion.