It should be emphasized that infinite quantities are accumulations of infinitely many finite quantities. In the process of a known finite quantity accumulation (add), if the accumulation is close to a certain quantity, then we say that it can reach this quantity, or it can reach this quantity by accumulating forever, and we define the quantity as finite. If the accumulation is not close to a certain quantity, then we say that it cannot reach this quantity by accumulating it forever, and we define this quantity as infinite. From the above three points of definition of infinity, we can see that infinite quantities are accumulations of infinitely many finite quantities.