Pliny the Elder, Natural Histories 31.88-89
“By Hercules, then, life can not be lived humanely without salt—it is such an essential substance that its name is transferred to powerful mental pleasures too. All the charm and the greatest humor of life along with rest from work are called salts (sales)—it rests on this more than any other.
It is also present in political offices and military service in the word salaries—which attests to its great authority among ancient speakers, just as is clear from the name of the Salarian Way by which it was agreed that salt would be carried to the Sabines. The king Ancus Marius granted a gift to the people of 6000 measures of salt and was the first to have salt pools constructed. Varro is also our expert here, indicating that the ancients used it as a condiment; and the fact that they ate sale with bread is clear from the proverb.
But a special proof still comes in sacrifices, since they can not be completed without salted meal.
ergo, Hercules, vita humanior sine sale non quit degere, adeoque necessarium elementum est uti transierit intellectus ad voluptates animi quoque nimias. sales appellantur, omnisque vitae lepos et summa hilaritas laborumque requies non alio magis vocabulo constat.
honoribus etiam militiaeque interponitur salariis inde dictis magna apud antiquos auctoritate, sicut apparet ex nomine Salariae viae, quoniam illa salem in Sabinos portari convenerat. Ancus Marcius rex salis modios v͞i͞ in congiario dedit populis et salinas primus instituit. Varro etiam pulmentarii vice usos veteres auctor est, et salem cum pane esitasse eos proverbio apparet. maxime tamen in sacris intellegitur auctoritas, quando nulla conficiuntur sine mola salsa.