As he was going through the last village, there stood a scissors-grinder with his barrow; as his wheel whirred he sang --
"I sharpen scissors and quickly grind, My coat blows out in the wind behind." Hans stood still and looked at him; at last he spoke to him and said, "All's well with you, as you are so merry with your grinding." - "Yes," answered the scissors-grinder, "the trade has a golden foundation. A real grinder is a man who as often as he puts his hand into his pocket finds gold in it. But where did you buy that fine goose?"
This is a short story "Hans in Luck" from Grimms' Fairy Tales. Could you teacn me the meaning " the trade has a golden foundation "?