God makes a covenant with Noah and his family. As we read today's reading from Genesis we hear God repeat the blessing he first uttered at creation: "Be fruitful, multiple and fill the earth". He re-establishes man as the preeminent creature on earth, but also as one which must be the most responsible. He outlaws the murder of other human beings because they are created in the image and likeness of God.
The covenant God makes here is with all the earth, all creation, and the sign of this covenant is the rainbow. This covenant prepares for the one the Lord will make with Moses and then the New Covenant in Christ. God is making peace with the earth and humanity as the first step towards redemption. In this covenant God promises to sustain creation and the natural order - he will not send another flood. As God makes this promise, his side of the covenant, Noah and his descendents must fulfil theirs, and this is symbolised by the ban on consuming blood. This is of course a looking towards the kosher laws of the Mosaic covenant, but here I think we can see another meaning.
Blood, for the Jews and other ancient peoples was seen as the principle of life, as God points out in verse 4, so it has to be respected. Here God is telling humanity to respect life and the natural order, and the law which will govern this is the natural law: that which is written in our very humanity. The natural law is that which is the most basic of laws and it provides the foundation for the divine law when it is revealed to Moses and then by Jesus. When that law is heeded that peace which existed between God and the earth following the flood is maintained, order is maintained.
Some examples: natural law tells us murder is wrong (and so abortion is wrong since it is murder - the killing of the innocent). Stealing is wrong. Adultery is wrong since it is the betrayal of an intimate relationship. These are basic transgressions that we know are wrong by instinct. But natural law also tells us that certain relations are wrong - between people of the same sex, between humans and animals, since such relations contradict the natural order of our bodies and the process of reproduction.
We live in an age when natural law is denied and fought against. Goverments and legislatures have abandoned this most basic and sound rule of life, and as they do so society begins to suffer. People may ask, why is society in melt down mode in so many places? Perhaps it is because we no longer want to adhere to what is most human and natural, but seek to manipulate it and when we do find we create problems for ourselves.