Divine Mercy Sunday
Today, the Church's Liturgical Calendar celebrates Divine Mercy Sunday, a day especially dedicated to remembering God's mercy.
Jesus appeared to Saint Faustina Kowalska over a period of many years, detailing his Mercy to her, urging her, a cloistered nun, to make this message known to the world and to promote the image shown at the right. The white ray represents the water which flowed from side of Jesus when struck the lance after his death on the cross. This water represents the waters of baptism which makes souls righteous. The red represents his blood which is the life of souls.
He also asked her to promulgate a chaplet for the faithful to pray to seek God's mercy for themselves and others. It's prayed using regular rosary beads and the details can be found at the link above. It's relatively short, taking less than ten minutes, but when prayed well, really reminds you of the vastness of God's mercy and how dependent we are on it.
Her diary, Divine Mercy in My Soul, is a really good, albeit long, read. It's definitely recommended as it shows both how wonderful Christ's mercy is and how needful we are of it. It's also an excellent treatise on the value of suffering, how my offering up our suffering in union with the suffering of Christ on the Cross, we can make a difference for ourselves and others. (This doesn't mean we have to seek suffering out, but when it inevitably comes along, we should take advantage of the opportunity to make lemons out of lemonade, so to speak.)
This is a wonderful feast actually requested by Jesus during one of his appearances to Saint Faustina. Any time is a good time to recall the mercy of God, but this is a truly excellent time since it's at his request.