First partner is a Contact Improv principle that encourages play and relational understanding with gravity.
We dance in a gravitational well and though we may at times connect with another person, our relationship with said gravity is there all the time. That makes this our first partner. When all the other people have driven home you will still be able to dance with that gravity well.
This encourages us to think of the earth as a partner. One we can connect with, engage against, roll on ect.
Ideas for Further exploration