Avoid making hasty judgments

An elderly man and his son, who was 20 years old, were seated on a train. As the passengers occupied their seats, the train began to move. Once the train started moving, the 20-year-old son, seated by the window, was overcome with excitement and noise. 
He reached his hand out the window and, enjoying the feel of the moving air, exclaimed, "Father, see, the trees are swaying!" The elderly gentleman grinned and admired his son's enthusiasm. A young couple sat beside the young man, attentively listening to the conversation between the father and son, and they were astonished by the young man acting like a six-year-old. Unexpectedly, the young man exclaimed once more with enthusiasm,"Father, see, the animals and the clouds are shifting along with the train!" 
The boy continued talking excitedly about the simplest things, like trees, the sky, and mountains, while his father listened patiently, as if he enjoyed hearing those straightforward sentences.
The young couple gazed at the boy with compassion. Rain began to fall. 
A couple of drops landed on the young man's hand, and he delightedly touched it, exclaiming once more, "Father, look! It's raining!" Water trickled onto his hand. The young couple could no longer endure it and inquired of the elderly man, "Why don’t you take your son to a doctor?" The elderly man remarked, "We are merely returning from the hospital. Today, for the first time ever, my son will be able to see."