Pars destruens/pars construens

Pars destruens/pars construens is like a seesaw. The "pars destruens" (tearing down) part is on one end, and the "pars construens" (building up) part is on the other. When you have to make changes, you have to first take apart (or destroy) the old things to make room for the new. And then you have to rebuild the new parts to get what you want. It's like renovating a house. You have to tear down the old parts first so that you can build the new ones.