From today's Gospel (Matt. 18: 1-5, 10, 12-14), one of my favorites right now:
"Amen, I say to you, unless you turn and become like children, you will not enter the kingdom of heaven...[W]hoever receives one child such as this in my name receives me...In just the same way, it is not the will of your heavenly Father that one of these little ones be lost."
