Or again, Luke is here describing the time before the descent to Egypt, for before her purification Joseph had not taken Mary there. But before they went down into Egypt, they were not told by God to go to Nazareth, but as living more freely in their own country, thither of their own accord they went; for since the going up to Bethlehem was for no other reason but the taxing, when that was accomplished they go down to Nazareth.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Metaphrastes.