This psalm was written after the people of God had been delivered from captivity.  In a Messianic manner their new freedom is a type of our redemption through Jesus Christ,  Now let us, too, be thankful to God for such a great deliverance, and honestly evaluated whether our response shows the same ecstasy and joy that comes when an illness is finally diagnosed as no longer life threatening.  Do we not at such a time breath a sigh of great relief and burst forth in words  that give all the glory to God.  Then note that all this rejoicing on the part of God’s people is followed by tears of sorrow for those still held in captivity.  Do we feel the same sorrow for those not yet set free by the salvation of Christ?    We live in sorrowful and troubling times today as traditional morals and sacred values are slowly eroding.  But be not depressed.  Instead turn to the words of the psalmist: “they that sow in tears shall reap in joy”.  In the end we, who have God’s sealed pardon and settled peace, also have that same promise of heavenly joy in Christ Jesus.