The fullness of time was now come, when God would send forth his Son, made of a woman, and made under the law. The circumstances of his birth were very mean. Christ was born at an inn; he came into the world to sojourn here for awhile, as at an inn, and to teach us to do likewise. We are become by sin like an outcast infant, helpless and forlorn; and such a one was Christ. He well knew how unwilling we are to be meanly lodged, clothed, or fed; how we desire to have our children decorated and indulged; how apt the poor are to envy the rich, and how prone the rich to disdain the poor. But when we by faith view the Son of God being made man and lying in a manger, our vanity, ambition, and envy are checked. We cannot, with this object rightly before us, seek great things for ourselves or our children.
[Excerpt from Matthew Henry's Concise Commentary]