<P> Modern commentators, authors Albert Jack and R. Richard Pustelniak, claim the original meaning of the expression was that the ties between people who've made a blood covenant were stronger than ties formed by "the water of the womb". However, no known historical sources support this . </P> <P> The use of the word "blood" to refer to kin or familial relations has roots dating back to Greek and Roman traditions. . This usage of the term was common in the English - speaking world at least as early as the mid 1300s . Because English speakers around that time would have understood the word "blood" as referring to family, it is likely that the use of "blood" in the expression "blood is thicker than water" would also have been understood by English speakers referring to family . </P> <P> Although not specifically related to the expression "blood is thicker than water", H.C. Trumbull notes an interesting comparison of blood and milk in the Arab world: </P> <Table> <Tr> <Td> "</Td> <Td> We, in the West, are accustomed to say that "blood is thicker than water"; but the Arabs have the idea that blood is thicker than milk, than a mother's milk . With them, any two children nourished at the same breast are called "milk - brothers," or "sucking brothers"; and the tie between such is very strong . (...) But the Arabs hold that brothers in the covenant of blood are closer than brothers at a common breast; that those who have tasted each other's blood are in a surer covenant than those who have tasted the same milk together; that "blood - lickers," as the blood - brothers are sometimes called, are more truly one than "milk - brothers," or "sucking brothers"; that, indeed, blood is thicker than milk, as well as thicker than water . </Td> <Td>" </Td> </Tr> </Table>

Where did blood is thicker than water come from