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The first implication of the tale is that sexuality is a practical matter. Production of children, not pleasure, are at the root of the story. This is perhaps the most forgivable aspect of the tale ethically because times were hard and there was a logic to the attitude. A pragmatic ethical polyamory or polygamy may be one logical lesson of this history, yet this is the one rejected by at least two of the Great Religions that derived from it. The story of Hagar understandably permits a more open attitude to concubinage in Islam but both Judaism and Christianity were to adopt a position where Sarah's matriarchal rights were to be privileged over both those of the patriarch himself and the concubine/first wife. For three thousand years, this has been presented as moral - but is it?
Far from being patrarchalist, Judaeo-Christianity starts its story, the story that then leads to Abraham and Isaac, with a tale of matriarchal struggle and power, of female competition. It tells us straight way that the subsequent three thousand years are the story of the triumph of one woman over another rather than that of a man over women. It undermines from the beginning the claim that Judaeo-Christianity is patriarchal and only patriarchal.
The second implication is the positive denial of emotion, of love, implicit in the story and the cruelty and resentment of the dominant matriarch. Abraham is twice denied his feelings by God - both here in regard to his feelings for Hagar and later in his feelings for Isaac on the sacrificial altar. God rewards the catty older woman over the younger. The 'patriarch' himself seems to have no power himself to bring the two women into line - it is his weakness before female rivalry that is the most noticeable feature of this part of the story.
What is going on here? Levantine man clearly had feelings. He was a human being. It seems that God does not approve of feelings, of emotion coming from within. Such emotion must be subordinated to the abstract - the theory of what is destined, written long after the event - and therein lies the tale. God's law, in the end, appears to suit Sarah as dominant wife and God himself as Authority. Patriarchal authority does not belong to the human patriarch at all - his wishes are ignored and he takes the easy way out. The authority belongs to an abstract and invented entity intended to buttress the power of the matriarch. It is as if the Great Goddess (if she ever existed) has proved a lot less useful than a Great Father because only through the latter can male physical power be re-appropriated for the real head of the household, she who is to be obeyed, though perhaps I take things too far and should not over-interpret the text.
But God does help Sarah to become dominant over Abraham in this matter and then takes Abraham away later to enforce his own direct dominance over him in the matter of Isaac. This is not a tale of patriarchal power at all but a tale of the assertion of priestly power (represented by this invented abstract thing called God) over the male by means of a Godly favoured female, a female given implicit domestic power in order to define the terms of the Law. The feminist analysis of Judaeo-Christianity is thus deeply flawed. It refers to patriarchalism when the Judaeo-Christian tradition is, much as Nietzsche described it, an alliance of weakness, of priests or intellectuals and middle class, property-owning women, designed to tame the free choices (which include sexual and emotional choices) of males and exclude other women.
This may not be a bad thing in itself because it depends where you stand in the game and there is only good or bad in relation to one's stance in that game. A certain form of order triumphed and made its rules stick. It is a contingent set of rules but, whether good or bad, it should still be seen for what it is and not for what it would be convenient for us to think it is in our later age. The Catholic Church, of course, took the Judaic system and went one better by (at least in theory) sexually neutering its priests so that all sexualities in the domestic setting were concentrated on the dominance of a mother advised by eunuchs. Marriage was to transfer the male from libertine to dog and excluded females to be sentenced to be sluts or nuns. Male sexuality and any female (or homosexual) sexual competitors were shunted to one side. God stood for an exclusivity that was prepared to eliminate (metaphorically and socially) its rivals through force of customary law, an elimination performed on Hagar.
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So, what was the cost of this system of social control designed to bring order to society (for that is what this story is about)? Abraham is weak - he allows his natural feeling for a woman and their child to be thrust aside by the strictures of priestly (God's) and matriarchal law. Natural feeling will be torn from him later (saved only at the last minute) but this first case is not just abandonment, it is also also attempted murder. Let us remember - both Hagar and Ishmael are sent into the desert, in effect, to die. So a weak man and a proud and manipulative woman (with a little help from an ideological construct called God) sentence a weaker woman and a child to death without once questioning the morality of their action. Yet this morality (or lack of morality) is at the very centre of Western culture. Is a murderous callousness at its very heart?