A Voice from the Past - Augustine of Hippo

It is evident, then, that the oldness of the letter, in the absence of the newness of the spirit, instead of freeing us from sin, rather makes us guilty by the knowledge of sin. Whence it is written in another part of Scripture, "He that increaseth knowledge, increaseth sorrow," -- not that the law is itself evil, but because the commandment has its good in the demonstration of the letter, not in the assistance of the spirit; and if this commandment is kept from the fear of punishment and not from the love of righteousness, it is servilely kept, not freely, and therefore it is not kept at all. For no fruit is good which does not grow from the root of love.

Augustine of Hippo, 354-430 AD, On the Spirit and the Letter, Chapter 26 (The Nicene and Post Nicene Fathers, 1st Series, Volume V, Philip Schaff, T & T Clark and Wm. B. Eerdmans Publishing, 1997, p. 94)

Is this a legitimate distinction? If so, how does it apply in our lives?