Etymology of "salarium" and its connection to salt

Question

It has been asked before both in the English Language & Usage site and the Spanish Language site about the etymology of salary and salario, respectively. In both cases, this site was mentioned as a more suitable place to ask this question, but it seems it has not been asked already.

Some texts say that the Latin word salarium comes from sal "because the Roman Legions were sometimes paid in salt". Or maybe they were paid to buy salt. A Spanish dictionary from 1611 (by Sebastián de Covarrubias) states that salt in this case must be understood as any type of food, as salt was added to almost any meal, so a salary was something you could buy food with. It also says that the reason could have something to do with the rents obtained with the salt marshes.

In any case, the question is: when and how did the word salarium originate in the Latin language? Does its etymology come from Latin sal? If so, what is its actual connection with the salt?

Answer 1

This book suggests:

SALARY, salaire, F. From salarium, L. a stated allowance of provisions given to a soldier, of which (sal) salt was a necessary part; and hence the term came to signify pay or salary.

This other book suggests:

SALARY. Of or belonging to salt. Money given to the soldiers for salt. (L. salarium.) (A. L.) [Andrew's Latin Lexicon]

Salt was held in great veneration by the ancients. It was always used in sacrifices; thus also Moses ordained, — "With all thine offerings thou shalt offer salt." Lev.ii.13.

Thus, to set salt before a stranger was, and still is, by some Eastern nations reckoned a symbol of friendship; and to spill the salt at table was esteemed ominous. The desire to obtain means for the purchase of salt gave rise to the word salarium, salary. (A. R. A., p. 312.) [Adam's Roman Antiquities]

This book states:

Whenever a word loses a definite denotation, its meaning is obviously generalized or diffused. Because people think with varying degrees of definiteness, we find an almost inexhaustible number of examples of generalization or blurring of meaning. For example, salary comes from the Latin salarium, 'salt money,' part of pay of the Roman soldiers. Ignorance and the lack of literacy have contributed their full share to linguistic change. Many of the words we use today retain the fossils of the past; we can see in them forgotten uses and customs.

This book has an interesting entry too. When listing words with the same origin but that are apparently so different (p.305), the following list about words derived from sal is included:

27. Sauce (L. salsus, Fr. sauce), saucer (Sp. salsera, Fr. sauciere) and sausage (Sp. salchicha, Fr. saucisse), salsify and salad (Sp. salado, salted), and saline and salary (L. salarium, lit. salt-money given to the soldiers, or a stipend) are all derived from L. sal, salt (Sk, sara-s, Gr. &Ag); as well as insular (= in sale).

On this same issue, this book states:

104. sal, salis, salt; stem, sal-, sali-

Related words: saline, salad, sauce, sausage, saltpeter, salary, saucer, saucy.

Salary is from salarium, 'salt money paid a soldier.' A saucer was a receptacle for sauce from salsus, 'salty,' which is derived from sal. A saucy person is one whose talk is 'salted,' sharp, or pert. Sausage comes through Late Latin salsicia from Latin salsus, 'salty.'

(so sausage comes from sal too! Who would have thought that!)