Here's the breakdown:
* Tried: In medieval metallurgy, "tried" referred to the process of testing a metal's quality by heating it in a furnace. This process would reveal any impurities or weaknesses in the metal.
* True: If the metal survived the trial by fire without failing, it was considered true, meaning it was of good quality and reliable.
The phrase "tried and true" eventually evolved to encompass a broader meaning, signifying anything that has been tested and proven to be reliable, trustworthy, and effective.
It's interesting to note that the phrase has a literal meaning rooted in a specific historical practice, but it has since become a figurative expression used in various contexts.