Newton's Third Law Tells the Whole Story

 When I was a student and I encountered Newton's Third Law, I did like most of my students do today: "Interesting, okay - but not too useful in problem solving so..."

In case you forgot, it's the one that goes "For every action there is an equal and opposite reaction".  Probably one of the more misleading statements in basic physics since it engenders many incorrect schemas in the reader's mind.  You can confirm this by doing a tour of the internet looking for examples of Newton's Third Law and I have found it to be commonly misrepresented ("A rocket first pushes down on the ground so it can then go upwards." Ugh, there is so much wrong with that statement, don't get me started.)

In class, I will usually draw something like this:

And then I will say "See, Newton's Third Law is really a statement about what forces are:  They arise from two objects interacting in some way." And then I mumble and fade away with "It's really a deep philosophical statement about the nature of reality."

The thing is, modern physics has really just continued to reinforce this idea that properties of objects and the nature of reality itself is all about the interactions between objects rather than the objects themselves.  Your chemistry teacher couldn't teach you how to visualize an electron because there really is nothing to visualize other than its interactions - which is exactly what you learn in chemistry!

Turns out Newton's first law assumes a certain point of view and Newton's second law assumed constant mass and that same, special point of view.  So even though they get the limelight, it's really the humble Third Law that is indicating something fundamental.

So get on out of here, you flashy first and second laws... time to give proper respect to the noble Third Law.