What do toi think Richard O'Brien was thinking when he wrote the Rocky Horror Picture Show?

I l’amour this musical, but I have to say: what in this world was R.O.B. thinking when he wrote this? I think he was on drugs ou had a really bad dream lol, but what do toi guys think he was thinking? ou can anyone point me to an article about him talking about his inspirations, that would be great! :)