Human Action: A Treatise on Economics by Ludwig Von Mises
This is the magnum opus of Ludwig von Mises. Being one of the best books on economics ever written, its philosophical content is often ignored. This is applied philosophy at its best, and a careful analysis will show a variety of ideas useful outside of this particular field.
"...a careful analysis will show a variety of ideas useful outside of this particular field." Do you have a specific citation? What impressed me most was that von Mises says that this book is only narrowly about "economics" and eventually he would write "all about" human action. That never came to pass. However, there is no doubt that people seek to optimize their situations. Values are subjective. People act to achieve them. Competition among providers delivers excellence. In sum, I consider this book spiritually uplifting. I read it at bedtime when I have nothing else to read. I just open a page I have not seen and read something new. The insights are edifying.
About 15 years ago, I went to my first and only "Star Trek" convention and met Aaron Shimerman who played Quark. He said that he was reading The Fountainhead in order to bring depth to his character. I mention that because the laws of praxeology ("human" action) must apply to any volitional being.
When I follow a knot of people into a public art museum and I see some people put five bucks in the donation box and other people not, I see human action.
When I worked for Coin World newspaper, I got the 50th anniversary "scholar's" edition for review. I kept that and donated my personal copy to the Amos Press library. It is amazing how many errors in economic thinking creep into numismatics, a hobby where people buy and sell money for fun.