Counting the Years from the Exodus and the Girl Gleaning Barley

"In the third month" - this tells that they count months from the Exodus from Egypt. I have only months; from where do I know years? Scripture teaches, "In the second year" (Numbers 1:1). I have only that period; from where do I know another period? Scripture teaches, "In the fortieth year of the children of Israel coming out" (Numbers 33:38). All these were before Israel entered the land. After Israel entered the land, from where? Scripture teaches, "And it was in the four hundred and eightieth year" (1 Kings 6:1). All these were before the House was built; after the House was built, from where? Scripture teaches, "And it was at the end of twenty years, in which Solomon had built." When they did not wish to count by its building, they counted by its destruction, as it is said, "After the city was struck" (Ezekiel 40:1). When they did not wish to count by their own reckoning, they counted by that of others, as it is said, "In the second year of Darius," and "In the second year of the reign of Nebuchadnezzar" (Daniel 2:1). And so it says, "If you do not know, O fairest among women" (Song of Songs 1:8), and it says, "Because you did not serve... so you shall serve your enemies" (Deuteronomy 28:47-48). Rabban Yohanan ben Zakkai was once going up to Maon of Judah, and he saw a girl gleaning barley from under the dung of horses. Rabban Yohanan ben Zakkai said to his disciples, "What is this girl?" They said to him, "She is a Hebrew." "Whose is this horse?" They said to him, "It belongs to an Arab horseman." He said to his disciples, "All my days I have read this verse and did not understand what it meant: 'If you do not know, O fairest among women.' You did not wish to be enslaved to Heaven; behold, you are enslaved to the basest of the Arab nations. You did not wish to weigh your shekels for Heaven, a beka per head; behold, you weigh fifteen shekels under the kingdom of your enemies. You did not wish to repair the roads and the streets that go up to the Chosen House; behold, you repair the posthouses that go up to the tables of kings." And so it says, "Because you did not serve" with love, "and you shall serve your enemies" in hatred; "because you did not serve" in plenty, "and you shall serve your enemies in hunger and thirst and want of all." Another interpretation: "and want of all" - lacking in the study of Torah.