Founder of the Passionists.
St. Paul of the Cross was a great mystic. I think most of us lay people - who on occasion imagine we know something about the spiritual life, mystical theology, contemplation and the dark night are terribly, grossly misled. From Garrigou-Lagrange:
His life was truly a life of reparation in all its depth and elevation; it was the apostolate by spiritual suffering to an exceptional degree. This suffering consisted not only in the subtraction of sensible consolations, but, as it were, in the eclipse of the virtues of faith, hope, and charity. The saint believed himself abandoned by God, he believed that God was irritated with him. His temptations to despair and sadness were overwhelming; and yet in this interminable trial, St. Paul showed great patience, perfect resignation to the divine will, and extreme kindness to all who approached him, as Father Cajetan relates.(20) In the Summary of the ordinary processes in view of his canonization, are the following declarations: "One day St. Paul said to his director: 'If anyone should ask me at any time what I was thinking about, it seems to me that I could reply that I was thinking of God.' " (21) This was likewise the case even in his greatest spiritual desolations, at a time when it seemed to him that he no longer had faith, hope, or charity. (22) He was accustomed to say: "It seems to me impossible not to think of God, since our spirit is wholly filled with God and we are entirely in Him." (23)
Actually, when St. Paul of the Cross went through the streets of Rome exclaiming: "A via Pauli, libera nos, Domine," he was unable to breathe spiritually except in God. Day and night for fortyfive years his prayer was a painful, heroic, incessant prayer, which sought God ardently, and which sought Him to give Him to the souls for whom this great saint suffered. More fruitful than years of preaching inspired by a lesser love, these painful years were a sublime realization of the Master's words: "We ought always to pray, and not to faint." (24) The saint's life and trials throw light on the import of the following thought of St. John of the Cross: "A single act of pure love can do more good in the Church than many exterior works". - Three Ages of the Interior Life: Part four: Ch 49: The life of Reparation