Ordeal of Fire

"Common iron prevails, more earthly than the 'noble' metals gold and silver, which cannot withstand the ordeal of fire. Though forcibly taken from its mother, iron emerges victorious, not destroyed but purified. It is the true child of Earth through tested worth, not just by right of birth." (Pesic 14)

These lines to me seem to be a profound symbolic statement, hinting on the direction that the sciences directed the world. I may be reading too much into it, but the elements paint a fitting picture on the value of scientific exploration. For science, most things to be useful must have a practical application. Iron is used for tools, not to look fancy or elaborate as gold and silver artwork. Iron is used for simple and sturdy equipment, such as plows to till the soil.

The interesting thing about this passage though is that iron can be transformed into something more useful. By trial of fire the iron can become stronger, while the "noble" becomes weaker.

Unsmelted iron was the natural sciences, coarse but still useful and good because they had a practical purpose. Perhaps the gold and silver are the humanitarian studies such as philosophy and politics. These cannot stand the ordeal of fire without loosing its integrity.

I have a couple questions: What exactly would the idea of fire consist of in this context? Does this ordeal have a positive or negative influence on the "blacksmith"? And why does he choose the words "more earthly"? Am I right in my interpretation that these words mean better or does Bacon recognize that "more earthly" simply means more applicable to this world?