Prince Siddhartha Gautama grew up in a palace and had everything that he ever wanted. His father was afraid that Siddhartha wouldn't be happy so everything in his son's life had to be perfect.
Then one day he visited a nearby city and came across an elderly man. He was so shocked at the sight of old age (as he had never seen it before) that he returned to the palace at once.
The next day, he revisited the city but was once again horrified. This time, it was the sight of a sick man lying at the side of a road. He had never before seen sickness, so he returned to the palace immediately.
On his next visit, he saw a dead man being carried through the streets in a funeral procession. This third sight struck him the deepest, he had never before seen death. Stunned, he returned to the palace.
He still visited the city again, but this time his experience was extremely different. He saw a holy man walking calmly through the crowd who was dressed in rags and was carrying a begging bowl. Something surprised Siddhartha though, the man had a deeply peaceful expression on his face.
After this experience, Siddhartha left his home and family to become a holy man. One day, he sat down next to a river and vowed he would he never rise again until he had found the truth.