We believe that water is H
O and that lightning is an atmospheric electrical discharge because these
identifications are parts of accepted theories with substantial explanatory power. The connection
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between lightning and electricity was first noticed in 1746 when the Dutch physicist Peter van
Musschenbroek developed the Leyden jar as a way of storing static electricity. Benjamin Franklin's
famous kite experiment in 1752 provided the first direct evidence that lightning is a discharge of
electricity. This hypothesis explained not only why sparks flew from the key that Franklin had
attached to the kite he flew in a thunderstorm, but also a broad array of observations about lightning,
such as its bright flashes, its production of loud sounds, and its ability to injure people. Demonstrating
that minds are brains is more complicated but is based on the same kind of reasoning, providing a
large array of evidence for which this hypothesis is part of the best explanation.