People often blame others for their own mistakes and sins. It's the fault of society, my upbringing, the media, and so on.
But Sirach insists that God has not commanded anyone to be wicked or to sin. God places before us two ways - the way of life, and the way of death. God asks us to chose life, but we are free.
If we chose, we could keep the commandments - we are responsible. Jesus did not abolish the Law - he raised the bar!
According to Matthew, believers are to surpass and outdo the Pharisees - they are to be super-observant. Doing just what is required, and nothing more is not an option - Jesus wants us to excel in righteousness.
It is not enough to merely avoid killing or committing sexual sin. We must also keep our minds free of these things. The thought is a father to the deed, as is said.
What we have in our thoughts eventually comes out in some way. Thoughts are potent; they create the world we live in. To guard our thoughts and to use our minds wisely and spiritually is a great gift that we can give ourselves and those around us.
Lord, may my thoughts as well as my deeds be pleasing to You.