After Osiris is tricked and killed by Seth he is dismembered, and it is up to his wife Isis to recover all the pieces and bring him back to life. There is something that always caught my attention about the way she does this, since there is a piece she can't recover (Osiris' penis).
One piece only she did not recover, for it had been eaten by certain impious fishes; and their kind were accursed ever afterwards, and no Egyptian would touch or eat them. [...] She gathered the pieces together, rejoined them by magic, and by magic made a likeness of the missing member so that Osiris was complete.
I have always wondered at the significance of having a missing piece, and that this piece is the one used to conceive. I have read several slightly different versions of this myth in which she is able to reconstruct it with magic or able to have a posthumous union with her husband and conceive in spite of the missing piece.
Could somebody clarify what is the importance of not being able to recover all the pieces of Osiris and the significance of the missing piece being Osiris' manhood?