With Happier Than Ever, her second full-length, seven-time Grammy winner Billie Eilish again took the No. 1 spot on the Billboard 200 albums chart. As for the album’s carefully crafted aesthetic, as Eilish explained to Jimmy Fallon on Monday night, the Happier universe started fully forming while she was at home one night listening to the late Julie London.

“I didn’t know what I was going to do at all until really almost when the album was over,” Eilish, who recently covered a London track, said around two minutes into the video below. “I didn’t know what it was going to be called, I didn’t know what the vibe was going to be, I didn’t know what the artwork should be. I knew, though, that I wanted it to feel very specific. I wanted it to have a real feeling to it and a real aesthetic to it. And then there was just one night when I was listening to Julie London and it was raining and my fire pit was on … It just hit me.”

Later, Eilish was asked about her proclivity for directing her own visuals, which she said simply comes down to having a vision and wanting to execute to the best of one’s ability.

“It’s a lot of work so, you know, sometimes I wish that I didn’t want to do it so bad,” she said. “I just really want to do it . t never worked for me before, really. I mean, sometimes it does. [But] I feel like when you have your own idea and you know what you want that sometimes the best way to go about it is to just do it yourself, even though it takes much more out of you.”

Eilish also discussed synesthesia (Fallon is a “vertical brown rectangle”), her upcoming sold-arena tour, and working with Robert Rodriguez. See more below.

Elsewhere, Eilish brought the title track to her new album to the Tonight Show stage. See that performance up top.