There comes a point where you start to assume others know what you know. Not in a paranoid ‘they’re in my head’ kind of way, but simply because you take a piece of knowledge for granted. That knowledge ceases to be special to you, you know it, you have known it for so long that you can’t remember not knowing it therefore everyone must know it too.

Recently I experienced this while monitoring an root excavation on a building site – plumbers were digging a trench just inside the Tree Protection Zone [see Tree literacy or just a guess?]. There was nothing special about the dig, exposed roots over 40mm in diameter were to be retained then covered, smaller roots were to be cleanly cut back.

We started digging and after about a meter we exposed the first lot of roots. The digger driver started plucking individual soil particles from the roots, the laser-level bleeped and sad FM played big-hair rock ballads from the 90’s – at this point Chris the master plumber arrived. In true building site fashion, work stopped and we all gathered at the side of the hole and looked.

Chris and the digger driver started asking about the roots and how we were going to get past them; hand digging was answer. From there we started talking about why we couldn’t use the digger – after all the digger driver was clearly very skilled (to see such dexterity out of a steel bucket was pretty amazing). But, as good as he was, he was still damaging the surface of the roots.

I explained that the outer layers of the root was the important bit; surely, they knew this – surely everybody knows this.

Chris the plumber is a wily old fox, I’ve worked with him before and clearly he was just trying it on – or so I thought. But, I wasn’t going to play his game, so I popped into the hole, cut a small root then proceeded to conduct an on-site root anatomy class. I knew they knew, but I was going to tell them again so they knew that I knew that they knew… but they didn’t.

Plumbers know about moving water through pipes, roots move water, roots look like pipes… are not roots pipes? There is a simple sort of logic there that could work, if roots were just like pipes; but they are not.  Water doesn’t surge through the center of a root.

Several hours later the trench was dug, exposed roots were covered and smaller roots were cleanly cut. The day was a success and as I went home trying to rid my mind of big-hair rock ballads I reminded myself that we should never take knowledge for granted – I know what I don’t know, but I should never assume that if I know something then others will know it too.