I heard this parable one day from a Nun and I decided to translate it in English for everybody. You can ask me Why? Because all people must be remember about all sins.
Parable
Many years ago in Russia, two women came in church for a confession. First woman cried and repented. She had one big sin. Second woman confessed that she did not have sins or had some but very insignificant sins and that she could not remember. After a confession the Priest stopped them and asked them to go with him to the river bank. Priest wanted the first woman to bring a big stone, but a for a second woman, she had to give him many small stones. When they did it, the Priest asked to bring all the stones back. It was an easy duty for the first woman, because she did not forget where she took her stone. The second woman could not do the same, because she did not remember, where she took her small stones, because there were a lot of them from everywhere. After that the priest said that it is easier to forgive one big sin, rather than many small sins.