I have a very small set of poems which I have found over the years that I really, really like .. and this is top of that list.  Incredibly it was written by a Dominican friar in the 13th century, named Henry Suso .. a little more about him after the poem.

The Finding  

  Now have I seen Thee and found Thee,
For Thou hast found Thy sheep;
I fled, but Thy love would follow--
I strayed, but Thy grace would keep.
Thou hast granted my heart's desire--
Most blest of the blessed is he
Who findeth no rest and no sweetness
Till he rests, O Lord, in Thee.

   O Lord, Thou seest, Thou knowest,
That to none my heart can tell
The joy and the love and the sorrow,
The tale that my heart knows well.
But to Thee, O my God, I can tell it--
To Thee, and to Thee, Lord, alone;
For Thy heart my heart hath a language,
For other hearts it hath none.

   In the wide world, speechless and lonely,
For me is no heart but Thine;
Lord, since I must love Thee only,
Oh reveal Thy heart to mine.
"Wouldst thou know My glory, beloved?
Know Me, the great I AM?
First must thine eyes behold Me,
The slain and the stricken Lamb.

   "My visage so marred more than any,
My form than the sons of men;
Yet to the heart I have won Me,
I am the fairest then.
Thou knowest the sun by his glory--
Thou knowest the rose by her breath,
Thou knowest the fire by its glowing--
Thou knowest My love by death.

   "Wouldst thou know in My great creation
Where the rays of My glory meet?
Where to My awful righteousness
The kiss of My peace is sweet?
Where shine forth the wisdom and wonder<
Of God's everlasting plan?
Behold on the cross of dishonour
A cursed and a dying Man."

Some biographical information gleamed from the internet gives an insihgt into Suso's life:

"Imagine bearing a cross to remind you of Christ's sacrifice. This is a common practice in Christianity -- contemplating the pain Christ bore for our sins. But now imagine bearing a cross, literally. This is what Henry Suso did for much of his life. Suso was so adamant about feeling Christ's pain and being reminded of his own ineptitude that he drove nails and needles into a wooden cross and strapped it to his back. This practice of self-harm for religious purposes is known as mortification, and Suso's autobiography profiles a perfect example of this unique custom. Along with many chapters on his suffering and how he made it through,"

He became known to me through two books, written by a sister, Frances Bevan: Three Friends of God and Hymns of Ter Steegen.

Suso was a member of 'The Friends of God'; a medieval mystic sect within the Catholic Church.

"The Friends of God are an informal group of Catholic mystics who organized themselves in Germany and Switzerland in the early 14th century. These Friends strove to deepen both their communal relationships as well as their inner spirituality. Tauler was a master of combining the mystical with the concrete, the spiritual with the practical. He taught that each human has a desire for God which is satisfied through detachment from earthly things. Suso also believed that to achieve perfect, soul-level union with God, a person had to die to himself and become detached from the world. History provides a "very imperfect sketch" of Nicholas Basle according to Bevan. For many years, Basle was thought to be the mysterious "Master" described in many of the Friends' documents, but it was later discovered that the Master was a fictional character. Bevan's book is a biographical narrative of these three Friends' lives complete with dialogue. They discuss numerous facets of Catholicism and mysticism, and readers interested in these subjects will enjoy the work."