Hello - Physics & calculus are what I can best describe as hobbies for me. Hobbies in the sense that I love these topics but work a regular job as an IT Manager through the day and then read whatever I can get my hands on in regards to these topics while 'burning the midnight oil'. Not sure if I have landed on a personal favorite among quantum physics, classical physics, or relativity. My college degree is in Economics. Interesting mix, I guess? None the less, on to my question for you: can someone recommend a good book that explains Feyman diagrams, how they grew out of the QED theory, and so on? I am currently reading a book called 'Quantum Gravity' - Smolin and think that I want to delve into these elusive Feyman diagrams next. Thank you.