The concept of an angel assigned to guide and nurture each human being is a development of Catholic doctrine that, although not specifically stated in Scripture, can be inferred from the words of Jesus in Matthew 18:10: “See that you do not despise one of these little ones, for I say to you that their angels in heaven always look upon the face of my heavenly Father.”
A feast in honor of the guardian angels was first observed in the 16th century. In 1615, Pope Paul V added it to the Roman calendar. The photo here is from Galleria Nazionale d’Arte Antica, Rome. Pietro da Cortona, 1656, oil on canvas.