The writing was the writing of God, inscribed on the tablets (Exodus 32:16).
The Talmud states that the word charus (inscribed) can also be read phonetically as chairus (liberty). The verse is thus telling us that Divine law which stresses using our minds to control ourselves provides true liberty and freedom.
In working with alcoholics and addicts, I have come to realize that the most absolute slavery does not come from enslavement by another person, but from enslavement by one's own drives. No slavemaster has ever dominated anyone the way alcohol, heroin, and cocaine dominate the addict, who must lie, steal, and even kill to obey the demands of the addiction.
Such domination is not unique to addiction. We may not realize that passion of any kind may totally control us and ruthlessly terrorize us. We may rationalize and justify behavior that we would otherwise have considered as totally alien to us, but when our passion demands it, we are helpless to resist.
Many people think they are free, yet they are really pawns in the hands of their drives. Like the addict, they are not at all in control, and do not have the fundamental feature of humanity: freedom.
Our only defense is to become masters over our desires rather than their slaves. We must direct our minds to rule over the passions of our hearts.