The *rules of our game* must be thoroughly understood.
We work some of the problems and read all of them. Working a problem
is like cutting down a tree and reading a problem is like looking at a
tree. We spend part of our time swinging axes to develop our muscles,
and we spend part of our time looking around to keep us from being dolts.
The mathematical and scientific forests really are interesting, and we
should all enjoy chopping and looking at the scenery.

We should all carry copies of (1.381) [a certain integral for the Bessel function of the first kind of order 0] so we can entertain ourselves the next time we get stranded in an airport or a jail.

A student who wants to learn where differential equations come from and how they are used should pay careful attention to the problems. To solve a great many problems rapidly and thoughtlessly is a waste of time.

If in connection with some of these problems a student begins to feel that solving problems in applied mathematics involves so many approximations that the whole business is utter nonsense, he is to be congratulated. He is perhaps approaching a point where he may begin to learn something about the manner in which mathematics is used in the sciences.

__ Ralph Palmer Agnew, in his textbook *Differential Equations.*