א וַיְהִי בִּימֵי אֲחַשְׁוֵרוֹשׁ הוּא אֲחַשְׁוֵרוֹשׁ הַמֹּלֵךְ מֵהֹדּוּ וְעַד-כּוּשׁ שֶׁבַע וְעֶשְׂרִים וּמֵאָה מְדִינָה
1. And it was in the days of Achashverosh – he was the Achashverosh who rules from Hodu and until Cush, seven and twenty and a hundred state.
The Talmud (Megillah 11a) teaches that “vayihee” is an amalgamation of “vay” and “hee,” words that connote sadness and mourning even onomatopoetically, as they sound like cries. The reason for this is because people who are past focused instead of future focused are naturally unhappy. Like a housewife who is constantly doting over her wedding album as if no new memories are worthy of attention, people who are constantly singing “Those Were the Days” are not focusing on positive moments in the present like those who sing “These Are the Days.”