Where does literalism end and interpretation begin?

The 7th day depends on what the 1st day is. If Monday is #1 then Sunday is #7. If Sunday is #1 then Saturday is #7. None of that is really relevant. What is relevant is the day one accepts as the Sabbath and what that person does on the Sabbath.
This has been an interesting thread to read. Everything we say or read is interpreted through the 'filters' of our experiences and knowledge. I think that is why Christ said we must be like children. Children don't have those 'filters' and accept almost everything as written or stated. Adults tend to apply too many worldly concepts to their input.
Think of what the word 'gay' means in today's society, and what it meant 50 years ago... or a thousand years ago. The Bible MUST be interpreted, even by literalists, so as to understand what was meant at the time it was written. If 'heart' at that time meant 'self' or 'feelings', then it doesn't matter what 'heart' means today.