When Jesus called Matthew, he was a publican. Today he would have been the repo guy who would seize your car when you'd missed a few payments.
Yet, Matthew left all, rose up, and followed Jesus...I like to say he left everything but his pen, because he went on to write the majestic Gospel that bears his name. In it, he presents Jesus as King of the Jews and seeks to prepare them to receive His kingdom.
After he was transformed, he would record and live Jesus' words, "Blessed are the merciful, for they shall obtain mercy."