Does "By a model" refer to "by means of a model"?

A model is defined as a mathematical construct which, (the rest of the sentence needs improvement as well)

___

The problem you've run into is that the original was either a translation from Dutch to English or was written by someone who is still learning English.

Was his English not good enough? Not sure:

oops - Hungarian, not Dutch

in any case, his written English was not very good

The sciences do not try to explain, they hardly even try to interpret,
they mainly make models. The word "model" is used to mean a mathematical construct etc

In the general sense, a model is not an explanation. It is not a scientific theory. It is merely a mathematical tool they use to try to mimic known observations, and then project them into the future for the purpose of making "predictions."

Which is basically what he already said. I'm just rephrasing it in a way that you might find easier to understand.

"Johnny" von Neumann was regarded by his contemporaries as a very intelligent man indeed: very rapid in comprehension - a common speculation has been which of Einstein and von Neumann was the more intelligent. It can fairly be said that Einstein made a very deep contribution to science in one area, whereas von Neumann made less deep (but still very significant) contributions in remarkably many areas. I think Eugene Wigner said it best: "Einstein's understanding was deeper even than von Neumann's. His mind was both more penetrating and more original than von Neumann's. And that is a very remarkable statement."

Wigner also said: "I have known a great many intelligent people in my life. I knew Planck, von Laue and Heisenberg. Paul Dirac was my brother in law; Leo Szilard and Edward Teller have been among my closest friends; and Albert Einstein was a good friend, too. But none of them had a mind as quick and acute as Jansci [John] von Neumann. I have often remarked this in the presence of those men and no one ever disputed me."

Informative.