Young Sheldon” has revealed the origins of “Soft Kitty,” the song adult Sheldon Cooper (“The Big Bang Theory’s” Jim Parsons) needs to hear any time he is sick.

In the episode entitled “A Sneeze, Detention, and Sissy Spacek,” flu season hit Medford and the titular young Sheldon (Iain Armitage) did whatever he could to try to avoid getting sick, including putting on his astronaut Halloween costume (complete with helmet!) — but unfortunately his efforts did not prove to be enough.

Struck down with illness, Sheldon laid in bed with a compress on his forehead and his mom (Zoe Perry) sang to him. After hearing the verse once, Sheldon smiled and asked for it again — the beginning of something that becomes a pattern for him.

“Young Sheldon,” which is executive produced by Chuck Lorre, Steve Molaro, Jim Parsons and Todd Spiewak, is the No. 1 new comedy in viewers, adults 18-49 and adults 25-54 and the No. 2 comedy in all of television, behind its predecessor “The Big Bang Theory.” The most recent episode saw 14.17 live+same day total viewers and 2.6 in the 18-49 demo.

“Young Sheldon,” which is airing its first season on the Eye, has already been renewed for a second season.

Watch the clip of “Soft Kitty” from “Young Sheldon” below:

“Young Sheldon” airs on Thursdays at 8:30 p.m. on CBS.