Etymology of the Word Salary

So I just learned that Roman Soldiers were paid in part in lumps of salt because salt was so expensive in the middle ages.  The Latin root word for salt, sal, and the distribution of it as part of the soldiers pay gives us the word "salary."  If a man wasn't adequate in battle then the Romans would say that he "wasn't worth his salt."  Margaret Visser wrote a book called Much Depends on Dinner that has proved a bottomless pit for cool info like that.