Before leaving for abroad for the first time to preach Hinduism, Vivekananda's mother wanted to know whether he is all perfect for this mission or not, she invited him for dinner. Vivekananda enjoyed the food that had the additional flavor of his mother's special love and affection. After the delicious dinner, Vivekananda's mother offered Vivekananda a dish of fruits and a knife. Vivekanand cut the fruit, ate it and after that his mother said, "Son, can you please give me the knife, I need it." Vivekananda immediately responded by giving the knife. Vivekananda's mother calmly said, "Son, you have passed my test and I heartily bless you for going abroad." Vivekananda surprisingly asked, "Mother, how did you test me? I did not understand."
Mother replied, "Son, when I asked for the knife, I saw how you handed it to me, you gave the knife by holding its sharp edge and kept the wooden handle of knife towards me. This way, I would not get hurt when I take it and this means you took care of me. And this was your test in which you passed. The person who thinks of others welfare rather than thinking about self has got the right of preaching the world and you have got that right. You have all my blessings."
This was the most important mark he left in the hearts of many he met in his lifetime - to think of others before thinking for self.