Answer
The invention of the microscope allowed us to see living organisms much more in-depth and allowed us to be able to see the actual cells that made up living things, therefore giving us proof that all living organisms are made of cells.
Work Step by Step
Microscopes allow us to see things more in-depth and in more detail. By being able to do this, we could actually see the cells that makeup living things, helping to demonstrate part of the cell theory.