A wonderful reference as shared by our animation instructors David Good to the students during body mechanics class.

“Check out the arcs on her hands, the stiffness of flexing muscles keeping her movements tight and accurate. But you only notice these things on a second viewing. What you feel is what the arcs etc combine to create. the principles are backstage things.
The principles are hidden and felt and always present but they point to an action…like they all combine to create something greater. So now that your starting to understand them and are working them into your animations use them to describe the feeling of muscles and mass and motivation so that we notice the those things and don’t notice the principles that make them up!” ~ David Good 

Join Puppeteer Lounge to learn character animation with Sony Picture’s animator David Good: