The readings for today might be synthesized as follows:

Sirach reminds us that we have a choice in how we act, that we are not forced, but can choose to follow God's will through our loyalty.

The Psalm response is a prayer in which we ask God to grant us the grace of discernment (but obviously before we can be granted that gift, we must use our freedom of choice to ask for it - we must be willing to take the risk of finding out what God wants of us).

Paul teaches us that the spiritually mature have a true wisdom - that God reveals this wisdom to us through the spirit (and how is it revealed? through the process of discernment, which comes about usually through faithful conversations with God as part of spiritually maturing).

Matthew continues his discussion of Jesus' sermon on the mount.  One could look at the discussion in verses 17-37 as prescriptions - don't even think of doing these things.  But I think that this sermon from Jesus is similar to a value statement - a set of core principles. It is not enough that we should value the poor in spirit, the sorrowing, the lowly, those who thirst for holiness, the merciful, the single-hearted, the peacemakers, the persecuted and the insulted.  It is not enough that we avoid the technical prohibitions of the old law, murder, adultery, and all the Ten Commandments "thou shalt nots."  Jesus calls us to be proactive in settling our grievances with others, to avoid anger, to be pure of heart, to be trustworthy, to have integrity.  This all leads up to His new statement to turn the cheek, to love our enemies (so, I read ahead).  To me these are the values of the the spiritually mature person, the person Paul says will have true wisdom, the wisdom that comes from God.  And to complete the circle, this is to me what true discernment will lead to - a oneness with God's will and a series of choices motivated by that perception of moving toward the person that God calls us to be.