D. Jason Cooper in his Esoteric Rune Magic theorises a link between the 3 aettir of the Elder Futhark and the tripartite Aryan caste system:
"In its simplest form, the theory is as follows. When the Aryan tribes swept from the steppes, they brought with them a society already divided into three groupings, which might be called protocastes."
He refers to the first Aett, Freyja's Aett as being the aett of the nurturer, the second aett, Heimdall's Aett as being the aett of the warrior and the third aett, Tir's Aett as being the aett of the priest/king.
In addition to being representative of the Aryan caste system Mr Cooper also proposes that they represent a three-fold system of initiation. The ancient Germanic system of magical initiation has 3 degrees of Apprentice, Fellow and Master. The Rune Gild is one organisation which follows this system. Universities continue to organise their academic degrees in a three-fold system, although Master is the second rather than the third degree. Mr Cooper makes reference to both the tripartite caste system and initiatory degrees in his book:
"The aettir not only imply an initiatory structure, each aett being one degree in a three-degree system, but they seem to reflect the age-old division of Aryan tribal societies, by the way, is not an occult theory, but an academic one associated most closely with G. Dumezil."
By working with the runes we engage in a magical process of initiation. We remember that they are the gift of the High Lord and Rune Master Woden Himself and it is He who initiates us.