I came across this poem written by a Benedictine monk and archbishop named Hrabanus Maurus, addressed to Abbot Grimold of St.Gall.

I think it is a rather beautiful celebration of spiritual friendship.

Then live, my strength, anchor of weary ships,
Safe shore and land at last, thou, for my wreck,
My honour, thou, and my abiding rest,
My city safe for a bewildered heart.
That though the plains and mountains and the sea
Between us are, that which no earth can hold
Still follows thee, and love’s own singing follows,
Longing that all things may be well with thee.
Christ who first gave thee for a friend to me,
Christ keep thee well, where’er thou art, for me.
Earth’s self shall go and the swift wheel of heaven
Perish and pass, before our love shall cease.
Do but remember me, as I do thee,
And God, who brought us on this earth together,
Bring us together to his house of heaven.

From Mediaeval Latin Lyrics [pdf], translated by Helen Waddell, p.109 (Latin original on p. 108).