This is pretty much how integration works, and calculus shows us that integrating any arbitrary function can be done this way. But really isn't not that hard t

This is pretty much how integration works, and calculus shows us that integrating any arbitrary function can be done this way. But really isn't not that hard to intuit. Take any arbitrary shape and draw any number of arbitrarily small rectangles inside it. It should be easy to see that by adding the area of each rectangle, you approach the area of the shape. As the rectangles get smaller, the combined area of the rectangles gets closer to the true area of the shape.