What does "spin straw into gold" mean? Thx
Context:
In fairy tales, heroes are often faced with formidable tasks, such as [spinning straw into gold] or counting the grains of sand on a beach.
According to the dictionary, spin here probably fits the entry :they make thread by twisting together pieces of a fiber such as wool or cotton using a device or machine.
But what is a straw here? dry stalks? So is it saying that spin the dry stalks into gold thread? I'm a bit lost.
Thanks!