Osiris plays a key role and is a central figure in the ancient Egyptian mysteries and in the magical system of the Golden Dawn. It was Osiris who was the beloved pharaoh of Egypt. It was Osiris who taught the people of the land of Egypt about farming. Osiris was and is one of the first "Green Men", in that he was also the god of vegetation. When Osiris became ruler over the land of Egypt, the people were engaged in the practice of cannibalism. Osiris helped them to evolve beyond cannibalism and to learn farming skills.
Osiris is the husband of Isis. After thousands of years,
all female goddesses became merged as an aspect of Isis, she too is central
to Egyptian symbolism. Isis was well known for her powerful magic, her
cunning and wisdom - she was the "breath of life" that brought
life unto what was dead. A good example of this is portrayed in the fable
of "The Legend of Isis and Ra" as well as in the tale of how
she restored her husband, Osiris back to life. Most scholars know of the
tragic story of the death of Osiris. He was murdered by his evil brother
Set. Set is equated with Typhon-Apophis of the Greeks. Set is the destructive
aspect that the alchemical principal must undergo, and thus be reborn
into a new and purified creation. That is exactly what happened to Osiris.
His death or as the alchemist would say his putrefaction was carefully
evolved through the power of Isis under the magical direction of Thoth.
For as Osiris died, through the power of Birth (Isis) under the authority and skill of Thoth (The Higher Genius) Osiris arose on the physical plane as the great avenging god Horus, his son. On the spiritual plane Osiris became the great god of the underworld. Like Christ he became the god that the Egyptians needed to become in order to be saved. What this means is that unless the initiate allows for the complete transformation of the self under the direct guidance of the Higher, no true and lasting power can be obtained. Osiris is the reconciler with the Lower Selfhood in which no birth or death is necessary. We can refer to it as "The Bornless One."
To the Egyptians one must become Osiris. In that no one can or could deliver the forty-two negative confessions in the hall of truth, because no one is perfect in earthly life. By identification with Osiris the candidate who stands in the Hall of Truth can indeed deliver the negative confession. The reason is clear, it is not him, but him in Osiris that is delivering the negative confession. The candidate in the Hall of Truth is redeemed by his unification with Osiris. This unification in the traditional Golden Dawn system takes place in the grade of 5=6, Adeptus Minor. Of the details I can speak no more.
In the Hall of the Neophyte it is the Hierophant who sits in the Osirisian position on the path of Samekh outside of Tiphareth. Osiris is the one in the Hall of the Neophyte who confirms the initiation on the new candidate. This is done after the candidate has taken the oath and is placed in the northwest part of the hall.