According to Germanic tradition the individual being is really a "Body-Soul," or psychosomatic complex. The body and it's appearance are different aspects of this, as are breath (athem), the inspiration (wode), the mind, the memory (personal as well as collective), the heart, the will and certain magical faculties which individuals may or may not have acquired.
Individuals may have more that some of these magical faculties, such as hamingja, which is a repository of personal luck or fortune. Acquiring these magical bodies or the strengthening of them is one of the main tasks of Northern Magic. All exercise the Will and of consciousness increases this power.
Because the psyche or soul and the cosmos or world are both symbolically seen as trees in Northern Magic, we can speak of a Germanic teaching of "Pschocosmology". This teaches the way of the linkages between the soul and the world. If the inner world of the soul is explored and understood, the gateways are opened to a greater understanding of the larger world.
The fact that both of these structures are symbolized by trees makes it all the more meaningful that the runes were almost exclusively carved into wood in their earliest usage, so much so that the word for a stick of wood, "stave", came to mean the same thing as "Rune."
The runestaves are literally and symbolically the bridge between the inner tree of the soul and the outer tree of the world. Both of which are modeled on the Yggdrasill pattern.
Brightest of Blessings,