When in the beginning God created heaven and earth, the first trace of the Father was the substance of things. Later the form was added. In the third place, there was the goodness. But the godly alone observe this difference in the creatures. The ungodly have no knowledge of it; for they know neither God nor the creatures, far less their use.
Moreover, the use of a thing concerns the Holy Spirit. He who sees the use of a thing sees the Holy Spirit, he who discerns the form or beauty of a thing sees the Son, and he who considers the substance and continuing existence of things sees the Father. These three—substance, form, and goodness—cannot be separated.
But in money a greedy person sees only substance, form, and weight; he is not aware that it is a trace of the Son. Nor does he consider the use of the thing, that is, what purpose it should serve—chiefly, of course, the glory of God, then the benefit of one’s neighbor. The ungodly do not discern the goodness of things, even though they look to some extent at the substance and the form. Thus the man who lacks affection does not see the use of wife or children.
Abraham, however, understood for what use Sarah was given to him—not for lust but as a help for managing the domestics and for begetting and bringing up children. Because the ungodly do not understand this, they are not affected by it; they are nothing but stones. Such insensibility and lack of affection is indeed an indication of their leprous nature.
Luther’s works, vol. 4: Lectures on Genesis: Chapters 21-25 p 195-196