Between Asgard and Midgard is the Bifrost.
Bifrost is the domain where the elements of existence that lie beyond our understanding become
assimilated into the faculties of the human mind. It is the “Knowledge,” and as such it is the destination for all those who wish to “Know Thyself.”
Scholar Andy Orchard suggests that Bifröst may mean "shimmering path." He notes that the first element of Bilröst—bil (meaning "a moment")—"suggests the fleeting nature of the rainbow," which he connects to the first element of Bifröst—the Old Norse verb bifa (meaning "to shimmer" or "to shake")—noting that the element evokes notions of the "lustrous sheen" of the bridge.
Wikipédia
Bifrost role is the knowledge and it is the tenet ascribed to this area, It is the point which is responsible for the acquisition of self-knowledge.
Traditionaly we reprent this step with the "dragon"
Then comes the dusky
dreki fljúgandi, dragon flying,
naðr fránn, neðan a gleaming serpent, up
frá Niðafjöllum; from Niðafjǫll;
berr sér í fjöðrum, he carries in his feathers
- flýgr völl yfir, - - he flies over the field -
Niðhöggr nái. Niðhǫggr, corpses.
Nú mun hon sökkvask. Now he will lie down.
Voluspa - 66
The symbol of the dragon is a useful image in all esoteric and alchemical traditions. The dragon is emblematic of the struggles of humankind with their own inner selves, as a knight battles the winged fiend in tales of old. Carl Jung often postulated that the dragon reveals itself in many forms through dreams: a demon, animal, old man, cave, or even a walled garden...
Bifrost is the most uneasy and even dreadful step to encounter.
For as one ascends on Yggdrasil in earnest connection with the Supernal realms of being, Bifrost "the shaking bridge", is the where the last remnants of oneself —one’s image of oneself especially—is shredded.
Of course this is the great secret of the Hud and he who practices this ritual daily will have access to the higher worlds.
Knowing oneself completely, without shame, is true knowledge and it is the prime maxim of the mystery schools: “Over the doorway of many of the ancient temples was written
Gnothi Se Auton or, Nosce TeIpsum,
Know Thyself. make HUD. This psychological process is sometimes called ‘the unveiling of the self,’ sometimes ‘the knowledge and conversation of one’s holy guardian angel,’ or higher self. This is the first great goal.