The Rosary a mental prayer
The meditation on the mysteries of the Rosary is an essential condition for gaining the many Indulgences granted by successive pontiffs to this venerable Devotion. What is this but to repeat in other words that the Rosary, to be the Rosary, must be a mental prayer? If it ceases to be a mental prayer, it fails to be the Rosary. It may be a prayer — a vocal prayer — it is not the Rosary. The Rosary had to lead men to think, to lift up their eyes to the hills, to Him "who dwells in the heavens."
In what better and more simple manner can learned and ignorant alike be brought to "look upon Jesus the Author and Finisher of faith, who having joy set before Him, endured the Cross, despising the shame ; and now sitteth at the right hand of the throne of God" (Heb. 12:2), than in the mysteries of the Rosary? The Joyful Mysteries as a faithful mirror reflect "Jesus the Author and Finisher of faith"; the Sorrowful Mysteries in their five life-like pictures, portray Him to us "enduring the Cross and despising the shame"; the five Glorious Decades reveal Him to us "sitting at the right hand of the throne of God."