Let us consider a basic example of a model, a statue. The statue is considered as a model of that of which it is a statue in virtue of sharing a resemblance of its object’s form. Marble is said to be a statue of David when it has the shape or form of David. They are materially different, but formally similar and it is virtue of this formal similarity that the model is said to be a model of David.
Note that the model is oriented toward resemblance of David. Though they in a way share a form, David is primary and the model is secondary and derivative. David is never said to resemble the model, because he is the object and standard against which the model is judged.
However, the most distinct feature of this example is that this is a model of the quantity of David, that is his shape. Are there models of David’s qualities? An android is in someways a model of David’s qualities, including his power of locomotion. Certain complicated statistical software, sometimes called artificial intelligence, models certain human behaviors. A story and narratives can model life or events. So, it seems that a model has a formal similarity to its object.
There is however a difference in substance and essence. There is a certain likeness between a father and son. However, the son is no a model of the father in the relevant sense. The form of humanity to the is not just similar but the same. They are both essentially human and share the same form. David and his statue are not essentially the same, as David is a human and the statue is a block of marble in the form of David.