'God said' means the reply that was perceived. 'Truly Sarah your wife' means Divine Truth joined to Good. 'Is going to bear you a son' means that the Rational would come from this. 'And you will call his name Isaac' means the Divine Rational. 'And I will establish My covenant with him' means union. 'As an eternal covenant' means an eternal union. 'For his seed after him' means those who would have faith in the Lord.