Hi, Marjorie; I just happened to have read about this last
night! According to Ælfric's Homily on the Four Evangelists, Ezekiel had
a vision, wherein he saw four beasts, one in the appearance of a man, one
like a lion, one like a calf/bull, and one like an eagle.
These became associated with the Evangelists because:
Matthew gets the Man's likeness because 'he began his Gospel about
Christ's humanity'
Mark gets the Lion's likeness because 'he cried with a loud sound, even
as the lion roars'
Luke gets the Calf's likeness 'from the priest Zacharias because people
offered in the old fashion a calf for slaughter'
John gets the Eagle's likeness because eagles have keen vision and he
'beheld wisely how he might best write about God.
I am loosely citing from the EETS version of the Homilies, translated by
Skeat. If you are interested in having the Old English, let me
know.
Hope this helps!
cheers
Amy