There once was an old witch who lived up in the northern woods of Maine. She had moved farther and farther north because people have become afraid of witches these last several hundred years, and she felt it was best to stay out of their way. But it happened that she had moved so far north that she was too isolated to get the things she needed for daily life, and this did not suit her well at all. So she contrived a disguise one day, and anyone who lives here can tell you it was pretty clever. Simply put, she would transfigure herself into a cow and wander into a town to get the things she needed. No one pays much attention to a cow, after all, and this worked well for her for many years.
One day she wandered into a town to pick up some flour to make her pies and bread. A greedy farmer on the edge of town saw her and decided he would steal her add her to his herd. So he poked and prodded and whipped her until she ran into the corral with his other cows. Once she was secure within, he laughed and went indoors for supper. The old witch was very sad, but when she conferred with the other cows and learned of the farmer’s mistreatment of them all, she became furious. That night she cast a spell on the whole herd so that all the milk would be as sour as vinegar. When people came to buy their milk the next morning, they all returned it shortly thereafter because it was so horrible! That day the farmer made no money at all. The following day, the same thing happened, and then the day after that and the day after that still.
The farmer finally realized that it had all begun after he brought the new cow into the herd, so he went out to get her and slaughter her. When he arrived, she transfigured herself back into an old woman and ran at him with eyes ablaze. He fell to his knees and begged her forgiveness, but she would hear none of it. Right on the spot, she put a curse on him saying that if ever he mistreated his cows again, the milk would be sour as vinegar but that if he treated his cows well, the milk would flow and be sweet as honey. Then she left and took what little money he had in his pocket so she could go and buy her flour.
Of course, the farmer did not believe her and he mistreated his cows again for many weeks, whereupon immediately all the milk was soured and remained so. Then, beside himself with the fear of poverty and ruin, he brought the cows sweet grain, grass, and silage to eat and a beautiful pasture in which to eat it, whereupon the milk immediately flowed bounteous and as sweet as honey. Soon his customers came back, drawn by the sweet scent of fresh milk. They praised the farmer and paid him well and his pockets were full of money once again.
To this day, when the milk sours and tastes bad, you can bet an old witch is out and about teaching a naughty farmer a lesson. When the milk is good, you can bet that the farmer has learned his lesson, fed his cows well, given them green pasture, and housed them in a nice, clean barn. And if you want to be certain of good, sweet milk, you must buy it straight from the farmer and not from a store, where any kind of reverse magic may have been done to it. This is why the people of Maine drink fresh raw milk straight from the farm and why they thank the old witch every morning when they have their fair share.