Kant

Kant says that time and space are pure intutions. And he also says that the objection that the ideality of space and time turns the world of senses into illusions in vain. He says that not to the appearance of senses but judgement by the understanding. He uses an example but it wasn't clear to me. He also said that whether space is appearance or thing in itself has no bearing on this but the doctrine that space is appearance secures the objective validity of geometry. I did not really understand that section either.