David's language is deceptively simple, as he uses ordinary words to describe things which the rest of us ignore. Microscopic organisms, which we give scant attention to, are living organisms too.
In fact, David goes further, to suggest that those boundaries between living creatures and "inorganic'' elements may not be as definite as we like to think. Consider a box of metallic shavings. Certainly they are inorganic. We say they are not "alive". But if you put a magnet near them, those inorganic iron particles will start to dance. They form patterns and swirls. Yes, this movement is produced by a "magnet", but what is a magnet, but another piece of iron?
Living "creatures" are often complex structures. It is well known that "corals" are in fact 2 different organisms - one a plant, one an animal, working in cooperative harmony. But in a sense, we also are not just a single organism ourselves. For one thing what about the bacteria which live in our gut? We do not just "have" them, we need them. We would not function without them. They actually transform our food for us. So, are they not also "part of us". All is not as it seems. Life has far more mysteries up its sleeve than most of us have ever dreampt of.
David addresses many more issues than just these few, in his little book. I do hope that you get the chance to read it. It is available at the CTC in Robertson, for $25. I is a refreshing read - it is like having a massage for your brain.