Who wrote the book of love?

According to this story, the Irish abbot Brendan one day threw a book into the fire, as he refused to believe that the phenomena which the text described could have a real existence. Immediately an angel appeared who ordered him to set out to sea and see with his own eyes that which he refused to believe. And so Brendan set sail with a number of his mionks, one of wohm disappears in the course of the voyage. During his wanderings on the occean, Brendan sees the things he has read about: a fish with wood growing on his back and Judas enjoying a respite from hell on Sundays. He hears noises made by invisible people belopw the water’s surface. having witnessed these and many other amazing phenomena, he returns to Ireland after nine (or seven) years with a book in which his adventures have been recorded. There he dies and goes to paradise.

-- Clara Strijbosch, The Seafaring Saint: Sources and Analogues of the 12th Century Voyage of St. Brendan