Once upon a time, there was a very smart scientist named Dr. Smith. He was a brilliant inventor and had created many amazing things. One day, he decided to create a time machine. He wanted to travel through time and see what the world was like in the past.

Dr. Smith worked very hard on his time machine and finally, after many long days and nights, it was complete. He was so excited to try it out and see where he could go. He set the date for the year 1000 AD and stepped into the machine.

As soon as he arrived in the past, he realized that something was wrong. The world looked very different from what he had expected. He saw that the people were living in small huts and there were no cars or airplanes. Dr. Smith was amazed, but he also noticed that the people were very sick and there was no medicine to help them.

Feeling sorry for the people, Dr. Smith decided to give them some medicine from the future. He thought he was doing a good thing, but little did he know that this small action would have disastrous consequences for the present and future.

When Dr. Smith returned to his own time, he was shocked to see that everything had changed. The world was now a dark and dangerous place. The people were fighting and there was no peace. Dr. Smith realized that his actions in the past had caused a ripple effect that changed the course of history.

He tried to go back in time and fix his mistake, but every time he did, something else went wrong. Dr. Smith was faced with a dilemma - should he keep trying to fix his mistake or should he leave the past alone and accept the consequences?

In the end, Dr. Smith decided to leave the past alone and focus on making the present a better place. He learned that sometimes, even the smallest actions can have a big impact on the future. And from that day on, he used his inventions to make the world a better and safer place for everyone. The end.