How did Buddha teach Kisa Gotami the truth of life?

Kisa Gotami was devastated by the death of her son and she went from door to door, seeking help. Someone told her to talk to Sakyamuni, Buddha, who then asked her to procure a handful of mustard seeds. This raised hope in Gotami's heart that her son could be revived. But the condition imposed by Sakyamuni was that the seeds should be brought from a house where people had not lost a loved one to death. The futile search of Kisa Gotami made her realize that sorrows are a part of life and one can attain peace only by acceptance.