At that time the disciples came to Jesus and asked, “Who, then, is the greatest in the kingdom of heaven?” He called a little child to him, and placed the child among them. And he said: “Truly I tell you, unless you change and become like little children, you will never enter the kingdom of heaven. Therefore, whoever takes the lowly position of this child is the greatest in the kingdom of heaven. And whoever welcomes one such child in my name welcomes me.
Matthew 18:1-5 (NIV)