Preaching to the Choir - Learning for Environmentalists

I work with many environment and development groups working together in meeting/conference settings which often match content experts as speakers for audiences of members from their own community (e.g. sustainability experts talking to other sustainability practitioners). Depending on the level of intervention, this reflection often gets labelled as "preaching to the choir".  I'm sure this is a familiar occurrence.  I just heard  an interesting quote about this phenomenon:

"I'm preaching to the choir, which is challenging, because they are busy singing and can't hear you."

This quote made me smile and I found it particularly thought provoking because we might think that our "choir" (sustainability colleagues) doesn't listen because they already know the content, but perhaps they are not listening because they are mega-multi-tasking trying to get the message out themselves (if you see how many people are on their email etc. during these events, it must be that :-)