Found somewhere online:
On the icon of the Nativity of our Lord, the whole Gospel message of the incarnation of our Savior from the Virgin Mary is depicted, along with other details added from the holy Tradition. On many icons of the Nativity, there are a multitude of details, on others less. On the diagram shown here, taken from a drawing for an icon, we can identify at least 8 major elements.
(1) The focus of the icon, of course, is on the birth of our Lord from His most pure virgin mother Mary;A rough drawing of an icon of the Nativity of our Lord She is shown larger than any of the other figures, reclining on a mat, and looking not at her new-born Son, but rather with love and compassion towards her spouse, St Joseph the Betrothed (7), seeing his affliction and bewilderment over this most strange and divine birth;. He is shown in the left bottom corner, conversing with Satan, disguised as an old shepherd. The posture of St Joseph is one of doubt and inner trouble, for he wondered if it might be possible that the conception and birth were not by some secret human union; how blessed he was to serve the Mother of God and her divine Son, in spite of these thoughts and temptations, and to protect her from the evil gossip of the people who could not yet possibly understand so great a mystery. Our Lord is shown in swaddling clothes and lying in a manger, “for there was no room for them in the inn.” (cf. Luke 2) The back-drop for the manger is a dark cave (3), which immediately reminds us of the cave in which our Lord was buried 33 years later, wrapped in a shroud. In the cave are an ox and ass, details not mentioned by the Gospels, but which are an invariable feature of every icon of the Nativity; the scene is included to show the fulfillment of the words of the prophet Isaiah, “the ox knows his Owner, and the ass his Master’s crib, but Israel does not know Me, and the people has not regarded Me” (Isaiah 1:3). (2) Above this central composition, in the very center of the icon is the wondrous star coming from heaven, which led the magi (6) to the place where our Savior lay; It reminds us of the heavenly orb we see on icons of the Theophany, or Pentecost, wherever divine intervention is indicated.
The holy angels (4) are seen both glorifying God and bringing the good tidings of the Lord’s birth to the shepherds (5). The fact that Jewish shepherds and heathen magi were among the first to worship our Lord shows us the universality of this great event, meant for the salvation of all mankind.
The final detail of this icon, the scene of the washing of the Lord (8) is an element that has caused some controversy over the ages. In some churches of the holy monasteries of Mount Athos, the scene in the frescoes has been deliberately obliterated and replaced with bushes or shepherds; there was a prevailing opinion that this scene was degrading to Christ, who had no need of washing, being born in a miraculous manner from a pure virgin. But we retain this image on our icons, being part of the holy tradition passed on to us; truly it does not degrade the Lord, but magnifies Him, as is evident in the prayer that is appointed to be read at the time of Baptism for the midwife of a child: (From the Old-rite Potrebnik, 2nd Prayer for the midwife) “O Master, Lord our God…Who didst lie in a manger and didst bless the midwife Salome* who came to believe in an honorable virginity… ” [*according to Tradition, Salome was a daughter of St Joseph by his previous marriage] Who, more effectively than a midwife, could testify to the divine and virginal birth? Therefore we do well to understand the importance of this blessed scene.
Finally, as we look at the icon as one united composition, we can only be filled with joy, not only because of the bright colors and the festive activity depicted thereon, but for the joyous news of our salvation so clearly proclaimed by it. In it, all creation is rejoicing at the birth of our Lord: the heavens (a star and angels); the earth (the mountains, plants and animals}; and especially mankind, represented most perfectly in the figure of the new Eve, the most pure Mother of God.