ash, ashes, dust

Facts

Ash is the grey powdery substance that is left over after wood is burned. It is also the name of a kind of tree.

The term "ashes" is used figuratively in the Bible to refer to something that is worthless or useless.
In ancient times, sitting in ashes was a sign of mourning or grieving.
It was the custom to wear rough, scratchy sackcloth and sit in ashes or sprinkle the ashes on the head.
Putting ashes on the head was also a sign of humiliation or embarrassment.
When someone is striving for something worthless, it is said to be like "feeding on ashes."
In the Bible sometimes the word "dust" is used when speaking about ashes.