Four Zoas, Night V, PAGE 62, (E 342) "His loins inwove with silken fires are like a furnace fierce As the strong Bull in summer time when bees sing round the heath Where the herds low after the shadow & after the water spring The numrous flocks cover the mountain & shine along the valley His knees are rocks of adamant & rubie & emerald Spirits of strength in Palaces rejoice in golden armour Armed with spear & shield they drink & rejoice over the slain Such is the Demon such his terror in the nether deep But when returnd to Golgonooza Los & Enitharmon Felt all the sorrow Parents feel. they wept toward one another And Los repented that he had chaind Orc upon the mountain And Enitharmons tears prevaild parental love returnd Tho terrible his dread of that infernal chain They rose At midnight hasting to their much beloved care Nine days they traveld thro the Gloom of Entuthon Benithon Los taking Enitharmon by the hand led her along The dismal vales & up to the iron mountains top where Orc Howld in the furious wind he thought to give to Enitharmon Her son in tenfold joy & to compensate for her tears Even if his own death resulted so much pity him paind But when they came to the dark rock & to the spectrous cave Lo the young limbs had strucken root into the rock & strong Fibres had from the Chain of Jealousy inwove themselves In a swift vegetation round the rock & round the Cave And over the immortal limbs of the terrible fiery boy In vain they strove now to unchain. In vain with bitter tears To melt the chain of Jealousy. not Enitharmons death Nor the Consummation of Los could ever melt the chain Nor unroot the infernal fibres from their rocky bed Nor all Urthonas strength nor all the power of Luvahs Bulls Tho they each morning drag the unwilling Sun out of the deep Could uproot the infernal chain. for it had taken root"
Jealousy is rooted in the inability to be confident in one's own abilities and status. Los was unable to view Orc as other than threat to his own position. Even when he intended to release Orc - his emotions - he found that his resistance had been hardened to the extent that he was not capable of freely expressing his emotional nature which he had projected onto Orc .
It is important to remember that although Orc was portrayed as the son of Los, he was also the fallen form of Luvah. Blake was using the reaction that Los had to the entanglement of Enitharmon with her son, to explore the relationship of the Imagination and the Emotions as expressed in a fallen world. Another dimension of the relationship of Los and Orc was between each representing a different approach to change - either incremental or through revolution. But the point that is made most clearly in this passage is that many decisions are irrevocable.