Blacksmiths of the past had to work hard at hammering iron into shape. The iron was first heated in the fire until it was red-hot and malleable. The blacksmith would then remove the iron from the fire and shape by way of repeated blows from his anvil.
It was imperative that they work quickly before the iron cooled because once the iron was cool, it became brittle and could no longer be hammered into shape. However, once the iron was removed from the fire, the iron would cool very quickly.
Since it took longer to heat the iron until it was red-hot than it took for it to cool, blacksmiths kept multiple pieces of iron in the fire to heat simultaneously. In that way, the blacksmith always had a piece of iron red-hot and ready for hammering.
However, if the blacksmith had too many in the fire at the same time, he couldn’t keep track of them all and he could not attend to them properly as they needed his attention. When this happened, it was the sign of an inefficient blacksmith or one who had an unskilled apprentice working alongside him.
Historically Speaking 