Now, this idea about the arrows is itself very significant of the mental attitude of primitive man, and of the way that mental attitude has coloured all subsequent thinking and superstition upon this very subject.  Curiously enough, to the present day the conception of the thunderbolt is essentially one of a bolt—­that is to say, an arrow, or at least an arrowhead.  All existing thunderbolts (and there are plenty of them lying about casually in country houses and local museums) are more or less arrow-like in shape and appearance; some of them, indeed, as we shall see by-and-by, are the actual stone arrowheads of primitive man himself in person.  Of course the noble savage was himself in the constant habit of shooting at animals and enemies with a bow and arrow.  When, then, he tried to figure to himself the angry god, seated in the storm-clouds, who spoke with such a loud rumbling voice, and killed those who displeased him with his fiery darts, he naturally thought of him as using in his cloudy home the familiar bow and arrow of this nether planet.  To us nowadays, if we were to begin forming the idea for ourselves all over again de novo, it would be far more natural to think of the thunder as the noise of a big gun, of the lightning as the flash of the powder, and of the supposed ‘bolt’ as a shell or bullet.  There is really a ridiculous resemblance between a thunderstorm and a discharge of artillery.  But the old conception derived from so many generations of primitive men has held its own against such mere modern devices as gunpowder and rifle balls; and none of the objects commonly shown as thunderbolts are ever round:  they are distinguished, whatever their origin, by the common peculiarity that they more or less closely resemble a dart or arrowhead.

Let us begin, then, by clearly disembarrassing our minds of any lingering belief in the existence of thunderbolts.  There are absolutely no such things known to science.  The two real phenomena that underlie the fable are simply thunder and lightning.  A thunderstorm is merely a series of electrical discharges between one cloud and another, or between clouds and the earth; and these discharges manifest themselves to our senses under two forms—­to the eye as lightning, to the ear as thunder.  All that passes in each case is a huge spark—­a commotion, not a material object.  It is in principle just like the spark from an electrical machine; but while the most powerful machine of human construction will only send a spark for three feet, the enormous electrical apparatus provided for us by nature will send one for four, five, or even ten miles.  Though lightning when it touches the earth always seems to us to come from the clouds to the ground, it is by no means certain that the real course may not at least occasionally be in the opposite direction.  All we know is that sometimes there is an instantaneous discharge between one cloud and another, and sometimes an instantaneous discharge between a cloud and the earth.