So I entered the place where I usually prayed and mindful of the words of the holy man I began to say, "Holy God". At once I was so greatly moved to tears and loving desire for God that I would be unable to describe in words the joy and the delight I then felt. I fell prostrate on the ground, and at once I saw, and behold, a great light was immaterially shining on me and seized hold of my whole mind and soul, so that I was struck with amazement at the unexpected marvel and I was, as it were, in ecstasy. Moreover I forgot the place where I stood, who I was, and where and could only cry out, 'Lord, have mercy,' so that when I came to myself I discovered I was reciting this. But who it was that was speaking, and who moved my tongue, I do not know - only God knows.

(Saint Symeon the New Theologian)