We hear in our first reading from the prophet Zechariah. This post-exilic figure is trying to reassure the people that their Messiah will come and will restore their fortunes. But then he specifies the nature and quality of this hero: he will enter Jerusalem, not on an Arabian charger, but on the foal of a donkey--and he will effectively disarm the nation, destroying horse and chariot! What could this possibly mean? No one really knew until a young rabbi, some five hundred years later, rode into Jerusalem on the foal of a donkey and mounted the victorious throne of a Roman cross.
Bishop Barron’s Sunday Sermons - Catholic Preaching and Homilies