In a traditional opera a character (I think she is 天女） says 到無夢與無醒方見性靈. I am learning Chinese so from what I can understand it means "In the place between wakefulness and dreaming see..." what what does 性靈 refer to? I know 性 means gender or nature and 靈 is spirit but what do they mean together?

Also is this sentence in Mandarin or in Classical Chinese?