Burn the mathematics

I was reading through a economics book and then found a reference to Marshall's disregard for mathematics which did not relate to real life examples. I think this is very important lesson for physicists where the one needs to ensure that the implications of a simulation model have physical relevance. Sharing it for reminding myself and all the fellow researchers !

Alfred Marshall wrote about the correct use of mathematics in economics in a letter to A.L. Bowley dated 27 February 1906:

[I had] a growing feeling in the later years of my work at the subject that a good mathematical theorem dealing with economic hypotheses was very unlikely to be good economics: and I went more and more on the rules -

1. Use mathematics as a shorthand language, rather than an engine of inquiry.
2. Keep to them till you have done. 
3. Translate into English. 
4. Then illustrate by examples that are important in real life. 
5. Burn the mathematics. 
6. If you can't succeed in (4), burn (3). 
7. This last I did often.