City and People in Need of Help

In a kingdom far away lived a very loving, blessed, and generous father. One of the father's greatest desires was to share his kingdom's wealth and blessing with others. He had seven sons whom he dearly loved. The father assigned each of his sons to travel to a city and gave each of them a very challenging and difficult task. The first son set out to embark on his journey and did not return. The second son left for the city following his father's instructions and did not return. The third son, dressed in a green robe, left for the city and also in search for his brothers and did not return.The fourth son embraced his task and journeyed high into the mountain, low into the valley, around the broad and crooked field, and through the stream and did not return. The fifth son invested more time in preparing for his trip to the city, and yet he did not return. The sixth son left for the city, and as he entered the city, he saw a large black dusty door, and he did not return. What could have happened to his sons? The father pondered and contemplated if he should send his last son into the city. Would he return, and would the father ever see his other sons again?