My Gods of the ancient Northmen has some extra articles added to the original, French text. One of these texts is about the Rigsthula in which Rig (who is usually equated with Heimdallr) brings forth the three levels of society. Another text is completely dedicated to Heimdallr. Heimdallr is probably the most difficult and mysterious Gods of Northern Europe. Even though the text is of 1959 (after a lecture of 1956) and of course by Dumézil, there are still some new (to me) and thought-provoking ideas in it. Regard my short text as an insufficient summery of the theories posed in the article Comparative remarks on the Scandinavian God Heimdall (1959) and if it caught your interest, try to hunt down the text yourself or the book in which is has been published.
The god Heimdall poses one of the most difficult problems in Scandinavian mythology. As all who have dealt with him have emphasized, this is primarily because of a very fragmentary documentation; but even more because of the few traits that have been saved from oblivion diverge in too many directions to be easily “thought of together,” or to be grouped as members of a unitary structure.
Thus opens the article. Still Dumézil manages to combine Heimdallr’s ‘features’, so let us see what he came up with.
First Dumézil connects Heimdallr to the Roman Janus as being the first God, watchman, but this part is not really worked out. Dumézil didn’t find a good comparison in Indian mythology and after telling that Heimdallr is the first and the last (the last of the old Gods to die during Ragnarok) he continues with other subjects.
Interesting is Heimdallr as the sky God.
Note finally that, in this perspective and by comparison with the Indian Dyauh, the celestial traits of Heimdall are fully justified, for, if he is not strictly speaking the sky, his is the most celestial of the Scandinavian gods. He is more celestial than Tyr who, even if he corresponds phonetically with Dyauh, has acquired a completely different significance. As Jan de Vries said, Heimdall “lives at the edge of the world, at the foot of the rainbow, but his palace is above the skies, in the Himinbjorg… The rainbow is the path that joins the limit of the horizon to the center of the sky; it is from above the sky at the top of the central axis, that the watch-god watches the whole circumference of the world.”
After this Dumézil ponders for several pages on the following aspects of Heimdallr: 1) him being “the white God”, 2) his connection to the ram, 3) his connection to the sea. In the end all comes together!
Heimdallr is connected to the ram primally for the reasons that a ram is called “heimdali”, that a ram fights with its head and a “kenning” for sword is “Heimdallrs head” and his gold teeth do not just refer to the sun, but to the gilding of the teeth of a ram growing old. That is 1) in a nutshell.
The connection to the sea, Dumézil finds in the fact that during Ragnarok, Loki takes the form of a seal to fight Heimdallr who apparently has such a look. Also, Heimdallr’s nine mothers are the waves of the sea and Dumézil has found several places in which the waves are compared to sheep (for example) and the ninth to a ram. The foam on top of it, could have given Heimdallr his whiteness. Nice comparisons are made with the Celtic myth about Gwenhidwy from which Dumézil got the information about waves being called ram and giving birth in groups of nine (or “eight plus one”).
Personally I find it all not completely convicing and I doubt that dissecting a mythological figure like this has any use in piercing through the mythological layer, but the article definately gives some things to think about and places Heimdallr in a different light.
For a completely different view, I like to refer to my article Fire in Northern Mythology.
Pure conjecture: Heimdallr’s head could refer to the crest (with some imagination it looks like a sword blade) of a wave (indeed the head of a wave) which crashes and strikes land over and over again. Eight sheep before the Ram would imply that the 9th wave is stronger. Therefore, the crest of that wave would achieve the greatest blow, not unlike a sword in battle.