On one occasion I was reflecting on the Holy Trinity, on the essence of God.
I absolutely wanted to know and fathom who God is.
…..In an instant my spirit was caught up into what seemed to be the next world.
I saw an inaccessible Light, and in this Light
what appeared like Three Sources of Light which I could not understand.
And out of that Light came words in the form of lightning
which encircled heaven and earth.
Not understanding anything, I was very sad.
Suddenly, from this sea of inaccessible Light came our dearly beloved Savior,
unutterably beautiful with His shining Wounds.
And from this Light came a Voice which said,
"Who God is in His Essence, no one will fathom,
neither the mind of Angels nor of man."
Jesus said to me,
"Get to know God by contemplating His attributes."
A moment later, He traced the sign of the cross with His hand and vanished.
From the Diary of St. Faustina
Divine Mercy In My Soul