Last week, I polled a dozen people under or slightly over age 30: “Ever heard of Rhoda?” Only two said yes.

Rhoda Morgenstern was the character played by Valerie Harper on “The Mary Tyler Moore Show,” the classic ’70s sitcom. The sad news that Harper has terminal brain cancer is reason to offer a refresher course on her greatest role.

Rhoda was Mary’s best friend … and the Liz Lemon of the ’70s. Really! Like Lemon, Rhoda could turn the world on with her sarcasm and eye rolls, was creative (she dressed windows at Hempel’s department store) and had food issues. Rhoda confronting a chocolate: “I don’t know why I should even bother to eat this. I should just apply it directly to my hips.” And both women had bad luck with guys. Rhoda once grazed a man with her car and invited him to a party; he came … with his wife. Rhoda to party-goers: “This is my date, Mr. and Mrs. Armand Linton.”

Rhoda’s fearless sense of humor about her very human frailties is why extremely old people like me love her, and why young’uns should start watching reruns of “The Mary Tyler Moore Show” (Familynet, weeknights, 8:30 p.m.).