From long experience I have learned that there is nothing like holy water to put devils to flight and prevent them from coming back again. The also flee from the cross, but return; so holy water must have great value. For my own part, whenever I take it, my soul feels a particular and most notable consolation. In fact it is quite usual for me to be conscious of a refreshment which I cannot possibly describe, resembling an inward joy which comforts my whole soul. This is not fancy, or something which has happened to me only once, it has happened again and again and I have observed it attentively. It is let us say, as if someone very hot and thirsty were to drink from a jug of cold water: he would feel the refreshment throughout his body.
I often reflect on the great importance of everything ordained by the Church and it makes me very happy to find that those words of the Church are so powerful that they impart their power to the water and make it so different from water which has not been blessed..
One night, too, about this time, I thought the devils were stifling me; and when the nuns had sprinkled a great deal of holy water about, I saw a hug crowd of them running away as quickly as though they were about to fling themselves down a steep place.
I will only describe something that happened to me one night of All Sous Day. I was in an oratory: I had said one nocturne and was repeating some very devotional prayers which follow it – they are extremely devotional: we have them in our office book – when actually the devil himself alighted on the book, to prevent me from finishing the prayer. I made a sign of the cross and he went away. I then began again and he came back. I think I began the prayer three times and not until I had sprinkled some holy water on him could I finish it.”
St. Theresa of Avila said she would die for one drop of holy water since what gave it it’s effectivity was the precious blood of Jesus. She believed this because of the ancient saying that you say when blessing yourself with holy water. “By this holy water and by thy Precious Blood wash away all my sins, O Lord.”