From time to time, there appear cute anecdotes from people "who knew they were old when..." My moment happened last year with two much younger male colleagues.
We had been talking, I don't remember exactly about what (another sign of age?), and one of them said, "I've never been to Mexico."
EVERYONE of the "right" age knows this song.
Thinking I was just so terribly funny, I said, with great deadpan delivery, "I've never been to Spain, but I kind of like the music" (the first line of the song).
Both of my much younger male colleagues, being polite young men, looked at me with great seriousness and said, "Oh, is that so." And "Oh, really."
Neither of them had ever heard of Three Dog Night, let alone this song. They showed that respectful and somewhat quizzical indulgence of old people who just don't realize that they are no longer hip.
I was thirty years and more out of date; neither of them was even born when that song was released. My time of being in the thick of things, of cultural references, had passed, and the fact was staring at me in the persons of two non-comprehending but courteous young men. At that moment, I knew!
So, without further ado, some nostalgia for the older persons among us and a little 70's culture for the young. And some 70's psychedelic visuals.