We have seen that we can find fits that are very close to the actual characteristics for diodes. But fits bear the same relation to characteristics as an image does to an object. Our observations are not perfect and there are distortions present. The same relation exists between a print and the typeset page from which it was made. It is impression versus form.
The ancient Greek philosophers assigned a greater reality to the forms than our perceptions of them. The problem is similar to that of doing fits with the patterns being somewhat imperfect. But the same pattern may be applicable to a number of similar objects (in our case diodes) with different coefficients in the characteristic equations.
In The Sophist Plato uses an "Eleatic Stranger" with extraordinary skill to try to capture what we mean by a sophist. The Stranger first uses the dialect method in an attempt to pin down the sophist but he proves to be an elusive quarry. He appears to be many things at once. After studying "being" and "not-being" and what we mean by these terms he comes to the conclusion that the sophist is a pretender. He does not possess or impart true knowledge. The dialectic is a process of defining a pair of cases to which the object in question either belongs or does not in order to specify what it is. The Stranger looks down on the Sophist and is cutting him at the same time. The Sophist does not rank with the Philosopher.
The case is not quite so bad with the fits but one still can't trust them completely. Theory might help narrow down equations to be fitted but measurements usually have errors associated with them and can produce unavoidable residuals as a result.