You’re familiar with the practical application of Boyle’s Law, whether you realize it or not.
Take a deep breath. Now exhale.
When you breathe in, your chest expands and your diaphragm drops. This increases the volume of your lungs. The air in your lungs has a larger volume to fill, so the pressure decreases, falling below the air pressure around you. Air flows into your lungs to balance things out.
When you breathe out, reverse the process.
Boyle’s Law is the part about a fixed amount of air dropping in pressure when the volume expands. (It’s okay if you don’t remember this from your high school physics class; I had to google it to make sure it was Boyle’s Law I was thinking of.)
When scientists call something a law, it’s because they’ve found it to be universal. It always applies, even if it’s something that you never really think about, like Boyle’s Law or the Law of Gravity.
Principles are how we apply a law to produce a desired effect. Bernoulli’s principle shows how we can use Boyle’s Law to create lift with an airplane wing. When properly controlled, this lift can overcome the Law of Gravity.
This is why pilots get paid the big bucks. Practices are situational. The specific and momentary needs of a plane change constantly while in flight. They have to know how to apply and adjust the right principles at the right time to make sure that gravity doesn’t abruptly take over.
Advice is generally situational. It makes assumptions about where you are and where you want to go and prescribes a path to traverse the gap. The more your particular starting line and finish line differ from the ideal (what the advice was designed for), the less applicable it may be in your situation. Executing the wrong practice can easily make a bad situation worse.
Even when advice doesn’t quite fit, you can still benefit from it. Take a step back and take it apart. What problem is it trying to solve? What solution is it trying to take you towards? What would need to be true for it to work?
If you identify the principle behind the advice, you can adapt it. You can synthesize your own advice that will take you where you want to go.
But even principles have limited application. If you want to really learn how to navigate your way, study the laws. Gain a deep understanding of the universal laws that govern your flight.
You can learn to do this from the bottom up or the top down. Start with the specifics and learn how they fit together. Start with the big picture and learn how to drill down. Either way works.
Understand how the laws work. Learn how to apply them, to work with them. They always apply, but with a little understanding, you can learn to fly.