The need.
A long, long time ago, when the first human settlements were barely sprouting along the great rivers, trade was a simple dance, a palpable need. A farmer, with his surplus grain harvest, sought the skin of a hunter. "I will give you ten handfuls of wheat for that deer skin," said the farmer. And so, with a hand gesture and a nod,
#trueque was born. It was the purest form of exchange, but soon showed its cracks: What if the hunter did not want wheat? What if the skin was worth not ten handfuls, but seven and a half? The "double coincidence of wants" was an insurmountable wall for progress.