H. Clay Trumbull 
The Covenant of Salt [EPUB ebook] 

As I have come to see it, as a result of my researches, the very idea of a ‘covenant’ in primitive thought is a union of being, or of persons, in a common life, with the approval of God, or of the gods. This was primarily a sharing of blood, which is life, between two persons, through a rite which had the sanction of him who is the source of all life. In this sense ‘blood brotherhood’ and the ‘threshold covenant’ are but different forms of one and the same covenant. The blood of animals shared in a common sacrifice is counted as the blood which makes two one in a sacred covenant. Wine as ‘the blood of the grape’ stands for the blood which is the life of all flesh; hence the sharing of wine stands for the sharing of blood or life. So, again, salt represents blood, or life, and the covenant of salt is simply another form of the one blood covenant.