Pope Francis has chosen the motto “Miserando atque eligendo”, meaning lowly but chosen; literally in Latin ‘by having mercy, by choosing him‘.
The motto is one the Pope had already chosen as Bishop. It is taken from the homilies of the Venerable Bede on Saint Matthew’s Gospel relating to his vocation:”Jesus saw the tax collector and by having mercy chose him as an Apostle saying to him : Follow me.“
(Alan: The Jews of Jesus' time considered "tax collectors" the most vile of sinners. In effect, they were the equivalent of American tax collectors who would surrender tax revenues to the very terrorists who blew up The Twin Towers. A Notre Dame theologian (and friend) argued that the impact of The Temple's destruction -- an act of villainy perpetrated by Rome's army-of-occupation in 70 A.D. -- was incalculably more significant to the ancient Jewish psyche than the effect of The Twin Towers' collapse on Americans. How so? By definition, the Twin Towers comprised a global financial center, whereas The Jerusalem Temple symbolized every religious aspiration of the Jewish people. Make no mistake. Jesus drank and feasted with the very people who extorted the money which then financed The Temple's total destruction. Here is an illuminating webpage that contextualizes the meaning of "Tax Collector" http://www.allaboutjesuschrist.org/tax-collector-faq.htm)
(Bede's) homily, which focuses on divine mercy and is reproduced in the Liturgy of the Hours on the Feast of Saint Matthew, has taken on special significance in the Pope’s life and spiritual journey.
In fact it was on the Feast of Saint Matthew in 1953 that a young seventeen year-old Jorge Bergoglio was touched by the mercy of God and felt the call to religious life in the footsteps of Saint Ignatius of Loyola.
Beyond the motto, the coat of arms has a blue field and is surmounted by the mitre and the papal keys. On the crest itself at the centre is the symbol of the Jesuits, a flaming sun with the three letters recalling the name and the salvific mission of Jesus. Underneath we have two more symbols: to the right the star representing Mary and to the left the nard flower representing Joseph.
The papal coat of arms and motto are the same that he used as bishop. The shield has a bright blue background, at the centre top of which is a yellow radiant sun with the IHS christogram on it representing Jesus (it is also the Jesuit logo). The IHS monogram, as well as a cross that pierces the H, are in red with three black nails directly under them. Under that, to the left, is a star representing Mary, Mother of Christ and the Church. To the right of the star is a nard flower representing Joseph, Patron of the Universal Church. With these symbols the Pope demonstrates his love for the Holy Family.
What distinguishes his coat of arms as pontiff is that, instead of the wide-brimmed, red cardinal’s hat atop the shield, it is now crowned by the papal tiara and crossed keys.
His motto—“miserando atque eligendo” (because he saw him through the eyes of mercy and chose him)—is taken from the Venerable Bede’s homily on the Gospel account of the call of Matthew. It holds special meaning for the Pope because—when he was only 17-years-old, after going to confession on the Feast of St. Matthew in 1953—he perceived God’s mercy in his life and felt the call to the priesthood, following the example of St. Ignatius of Loyola.