Leonardo knew more about pulling than most. His ambitious stage designs included elaborate and imaginative pulley systems designed to lighten the load of any poor stage hand who would otherwise be expected to shift scenery using sheer brute force.

These pulleys were used in sets and reduced the amount of force needed to lift a load by spreading it across a greater distance. In short, the more pulleys you have, the further you’ll have to travel to raise a heavy object. (The amount of effort needed to shift a heavy load can be worked out roughly by dividing the weight to be lifted by the number of pulleys available.)

So, in theory at least, a small child should be able to lift a herd of elephants just so long as he or she has enough pulleys and rope – and plenty of elephants. In reality, however, there is a limit to the number of pulleys we can use before friction between the rope and the pulleys causes the whole system to grind to an immovable and inevitable halt.

Although Leonardo used pulleys in his designs he doesn’t take the credit for inventing them. No one knows who did invent the pulley, but they were in use in Ancient Greece and possibly even earlier.