A poor boy is on the road, selling the goods from home to home. He has to pay the school fees from the commission he receives on the sales.  He left home long back and came very far from his home.  He was very hungry.  There is no money in his pocket except a five penny coin.

He knocked a door to ask some food to eat.  A young lady opened the door.  The boy hesitated to ask for food and asked for only water.  She invited him inside and made him to sit.

She returned back with one full glass of milk and told with a smile. "drink".

After he had the milk the boy asked how much he had to pay for the milk.

The young lady replied I know you are very hungry.  Because you had not asked but I only gave, you need not pay for it, again she smiled.

The boy promptly said, "My mother told me not to take anything from others free.  I should say thank you very much to you".  He left the home.

After some years the lady fell sick.  She was admitted to the hospital in the town nearby.

A doctor who had to look after this case had gone through the details and got surprised.  Immediately he visited the ward and identified the lady.  She was the same lady who gave him milk while he was being a young boy.

The doctor paid attention to her health and soon after she was discharged from the hospital.  The accounts section of the hospital sent the bill to the doctor first, as he requested so.  Later the bill came to her.

The lady thought she had to pay a big amount toward the bill.  She had gone through the bill and found the signature of the doctor under these words, "Paid in full with one glass of milk!"