It was Saint Matthew's fault. (I've been reading the Bible again.) "Ye are the salt of the earth", thunders the Authorised Version of 1611, "but if the salt have lost his savour, wherewith shall it be salted?" (Matt. ch. 5, v. 13). I love the stately grandeur of the King James, but for this passage, the New International Version (1984) is more appealing, with its talk of saltiness. (Of course, the original Greek has the salt being "made insipid", so it has definitely lost its savour and its saltiness!)
But I was reminded of the curious etymology of the word salary enshrined in the Oxford English Dictionary: "L. salarium, orig. money allowed to Roman soldiers for the purchase of salt, hence, their pay". No authority is cited. Perhaps it is the ridiculous assertion of Pliny the Elder, that master encyclopedist and perpetuator of myths and half-truths, that salt "was introduced into the rewards of war, from which we get the word salarium" (Nat. Hist. 31.41 ). It is well known that the word meant "pay". Pliny himself uses it as such (e.g. Nat. Hist. 34.6 , mentioning the salarium of a military tribune). But why?
Surely Roman soldiers didn't ever really get paid in salt.