David, unthinkingly, whilst being tended to by his mother, wishes for a third hand so that he could help and tie the knot that he needs his mother's help to tie. This of course, in a society and a household where conformity to the norm is so important, is something that is a shocking thing to say, and the way that his father explodes at him clearly demonstrates how, to Joseph, what is most important in life is adherence to religious precepts and laws. What David says as a throwaway comment that is not true suddenly, in his father's sight, becomes twisted into an appeal to the devil to be given an extra hand:
Were you, or were you not, expressing dissatisfaction with the form of the body God gave you--the form in His own image?
To Joseph, any relationship or kinship he can claim with his own flesh and blood, his son, comes second to religious law and keeping that law. The complete lack of understanding Joseph shows towards his son at this juncture, followed by the dream that David has of his father killing Sophie as part of a ritual sacrifice, clearly displays that the most important thing to Joseph is the eradication of mutations. This of course foreshadows the way that David's own father will later try to hunt his son down to kill him.