The bird on the wire
A bird sits on a bare high-voltage cable and is completely unharmed. Working out why is the best test of whether the last page made sense.
Figure to be added
Think about it first
The cable carries a very high voltage, and the bird is touching it directly with no insulation at all. Why is it not hurt?
The answer
The bird touches the wire at two places — but those two places are at the same potential. Since there is no potential difference between its feet, no flow of electrons takes place through the bird's body. So the bird is not shocked.
Voltage alone does not hurt anything
The cable's voltage is measured with respect to the ground, and the bird is not touching the ground. What matters is the difference between the two points it is touching, and that difference is almost nothing.
This is not a safety rule for people
A bird is small enough that both feet are a few centimetres apart on one wire. A person on a ladder is not, and a person is almost always connected to the ground somehow. Never treat the bird as evidence that a live wire can be touched.