Didn't all life start with the emergence of a border, a device that displayed the property to segregate a something from the environment?
By that an entity could emerge that is able to work by following its very own texture of rules and in the same time to communicate with its environment, this communication being vital for its very existence.
The structure that owns this ability of autoclosure on the one hand and openness on the other is the form of the membrane. Once the membrane was in the world life could evolve.
The premise of the membrane that until today guarantees the integrity of life is a condition we coined with the term immunity indicating that the immune system is in charge. This may be too short-sighted as all processes within the borders of an organism serve to sustain the integrity of what we call life.
Nevertheless this reduction is inevitable if we want to do the research on this topic. So let’s the whole melt down to the term immunity.
What you see on the image above, is no membrane, of course not. These lines have been the leftovers from some dirty water splashs that had dried up on the concrete pavement.
The membrane is a boundary that connects and disconnects, a delicate filter system that provides the equlibrium life depends on.