Searching in Google I discovered the sentence "Nature doesn't solve equations" is part of the title of a paper in chemistry, see paper 6 in:
http://www.inform.umd.edu/EdRes/Topi...ce/ChemConf97/
Not that this whole thing is particularly important, but I think it's kind of interesting. This is *not* from the original paper by Heyser, but the idea might be related to what Heyser meant, I think:
"Today we do admit, when challenged, that the natural phenomena happen without regard to the mathematics that we use to describe them. In other words we accept the fact that nature does not solve equations. But we are less comfortable when challenged to explain how the phenomena actually happen."
(From:
http://fie.engrng.pitt.edu/fie96/papers/253.pdf)
Next time I'm in a library will try to find the original paper written by Heyser in the Acoustics Eng. Society proceedings.
Cheers,
Raul