Ezekiel had a vision:
Ezekiel 1:10 (NIV)
Each [living creature] had the face of a human being, and on the right side each had the face of a lion, and on the left the face of an ox; each also had the face of an eagle.
The man face has a heart of compassion for the needs of others and the hands to help. The lion watches the horizon, sustaining and protecting. The ox sees the field in front of him, plowing back and forth. The eagle soars high above it all, with a vision for what has yet to come.