Once upon a time there was a goatherd in Ethiopia, called Khaldi (probably ancestor to many Ethiopian runners). He noted that the goats liked to eat some red berries and that they afterwards seemed more active.
Khaldi told some monks in the area about his observations. The monks went out and picked the berries and cooked them in hot water. When they had drunk the potion, they could stand to pray longer and with much greater enthusiasm than usual.