"if you wish to be perfect"

The lectionary reading for today is a favorite of mine, one I'd like to be reminded of again and again:

A young man approached Jesus and said, “Teacher, what good must I do to gain eternal life?”

He answered him, “Why do you ask me about the good? There is only One who is good. If you wish to enter into life, keep the commandments.”

He asked him, “Which ones?” And Jesus replied, “You shall not kill; you shall not commit adultery; you shall not steal; you shall not bear false witness; honor your father and your mother; and you shall love your neighbor as yourself.” The young man said to him, “All of these I have observed. What do I still lack?”

Jesus said to him, “If you wish to be perfect, go, sell what you have and give to the poor, and you will have treasure in heaven. Then come, follow me.”

When the young man heard this statement, he went away sad, for he had many possessions.