Where I’m from, trees bear fruit. A tree is an environment (a combinant environment by the way). Within that kind of environment are nodes at which things are combined and transformed in ways that make them specifically useful and close at hand. Such an environment is considered to be productive. tangerine tree
Models, as we have known them, are environments, and not particularly productive ones. That is changing now. We understand the difference between a barren environment, and an environment that will yield the nodes at which things are combined and transformed in ways that make them specifically useful and close at hand for work.
Please see: http://bit.ly/UsliAP