This is another network, the metabolic cycle. You can explore this image online.

It’s a map of all the biochemical reactions of earth. I have no idea what it means, like how to read it. Some people memorise parts of it; I just love looking at it.

In the centre – that circle right in the middle – is what’s called the Krebs cycle. This is a fossil of the whole cycle. Out of it comes fats, sugars and amino acids. If an organism can’t do all of this cycle, it has to eat something that does. Everything must participate in the whole of the Krebs. We’re going to zoom in on the bottom left of that circle.

Matt Webb, S&W, posted 2006-04-06 (talk on 2006-02-23)