"I don’t know exactly,” Charles Wallace said. “But I think it’s to find Father.”

Suddenly two eyes seemed to spring at them out of the darkness; it was the moonlight striking on Mrs Who’s glasses. She was standing next to Charles Wallace, and how she had managed to appear where a moment ago there had been nothing but flickering shadows in the moonlight Meg had no idea.

The above is from The Wrinkle in Time by Madeleine-LEngle

I understand that "spring" here means appearing suddenly (as if out of nowhere). But What does "spring at" mean?

I would appreciate it if you would comment.


Consider this example. If a cat sees a mouse, it will spring at the mouse. This means the cat will suddenly jump at the mouse with a lot of speed and energy.

The meaning of your text is this. The light reflecting from Mrs Who's glasses was like the two eyes of some animal that suddenly seemed to jump at Meg and her companions.