The Chain of Causes and Effects

Everything is said to be explained as soon as we have discovered its cause, or the reason why it exists. But no explanation of anything can be complete because human knowledge at its best goes but a very little way back towards the beginning of things. When a thing is found always to cause a particular effect, we call that effect sometimes a property, sometimes a power of the thing. A venomous snake is said to have the power to kill a man, because its bite may cause a man to die. Lead is said to has the property of heaviness, because it always causes us to have the feeling of weight when we handle it.