Okay, she thinks she just actually isn't going to be able to imitate Keltham's light source until he tells her what it is.

Okay, she predicts she just actually isn't going to be able to imitate Keltham's light source until he tells her what it is. Though there's no reason not to continue to try various combinations which she strongly expects not to get anywhere: sunlight with blue dancing lights to make up for the insufficient blue? No; dancing lights are too narrow. Overlapping a hundred hypothetical dancing lights at different points on the rainbow? She can't hold them all in her head.