Grasping Reality on TypePad, by Brad DeLong

...Scientific models are not self-evident things, and it is not obvious how such research objects are made, nor how a scientist reasons with them, nor to what purpose. These difficulties of definition and understanding are exhibited in a most concrete fashion in an example that lays claim to being the first such research object in economics...

<--I am of the school who holds that if Malthus could have built economic models, he would have done so...