Capacitors store a certain amount of charge, in that regard like a small battery. The voltage on the positive side is relative to the negative side.
If you have a 5V supply with respect to ground (your reference voltage), and you connect a capacitor between it and ground, it will charge to 5V.
If you then disconnect the capacitor and connect the negative side to the 5V supply, then the positive side will still be 5V relative to the negative side of the capacitor, but the positive side will be 10V with respect to ground.
Now take a second capacitor. Let's call the positive sides of the two capacitors as p1 and p2 respectively, and the negative sides for n1 and n2 respectively.
If you then connect a second capacitor in parallel with the first, so both n1 and n2 are connected to 5V, the charge will equalize between them. If you then connect n1 to ground, then p1 will be negative relative to p2 and charge will start flowing into capacitor 1 from capacitor 2.
Using transistors as digital switches, you can do this "dance" of alternating where you connect the negative sides to and thus move the charge along.
If you have a 5V supply with respect to ground (your reference voltage), and you connect a capacitor between it and ground, it will charge to 5V.
If you then disconnect the capacitor and connect the negative side to the 5V supply, then the positive side will still be 5V relative to the negative side of the capacitor, but the positive side will be 10V with respect to ground.
Now take a second capacitor. Let's call the positive sides of the two capacitors as p1 and p2 respectively, and the negative sides for n1 and n2 respectively.
If you then connect a second capacitor in parallel with the first, so both n1 and n2 are connected to 5V, the charge will equalize between them. If you then connect n1 to ground, then p1 will be negative relative to p2 and charge will start flowing into capacitor 1 from capacitor 2.
Using transistors as digital switches, you can do this "dance" of alternating where you connect the negative sides to and thus move the charge along.