In his The Last Battle, Lewis ventured out on a figurative limb with his Narnian characters in trying to capture Heaven’s essence in a way that might appeal to his young readers.
“Peter,” said Lucy, “where is this, do you suppose?”. . . “If you ask me,” said Edmund, “it’s like somewhere in the Narnian world. Look at those mountains ahead—and the big ice-mountains beyond them. Surely they’re rather like the mountains we used to see from Narnia, the ones up Westward beyond the Waterfall?”. . .
“And yet they’re not like,” said Lucy. “They’re different. They have more colors on them and they look further away than I remembered and they’re more . . . more . . . oh, I don’t know . . .”
“More like the real thing,” said the Lord Digory softly. . . .
“But how can it be?” said Peter. “For Aslan told us older ones that we should never return to Narnia, and here we are.”
“Yes,” said Eustace. “And we saw it all destroyed and the sun put out.”
“And it’s all so different,” said Lucy.
“The Eagle is right,” said the Lord Digory. “Listen, Peter. When Aslan said you could never go back to Narnia, he meant the Narnia you were thinking of. But that was not the real Narnia. That had a beginning and an end. It was only a shadow or a copy of the real Narnia which has always been here and always will be here: just as our own world, England and all, is only a shadow or copy of something in Aslan’s real world. You need not mourn over Narnia, Lucy. All of the old Narnia that mattered, all the dear creatures, have been drawn into the real Narnia through the Door. And of course it is different; as different as a real thing is from a shadow or as waking life is from a dream.” His voice stirred everyone like a trumpet as he spoke these words: but when he added under his breath “It’s all in Plato, all in Plato: bless me, what do they teach them at these schools!” the older ones laughed. It was so exactly like the sort of thing they had heard him say long ago in that other world where his beard was grey instead of golden. He knew why they were laughing and joined in the laugh himself. But very quickly they all became grave again: for, as you know, there is a kind of happiness and wonder that makes you serious. It is too good to waste on jokes. . . .
It was the Unicorn who summed up what everyone was feeling. He stamped his right fore-hoof on the ground and neighed, and then cried:
“I have come home at last! This is my real country! I belong here. This is the land I have been looking for all my life, though I never knew it till now. The reason why we loved the old Narnia is that it sometimes looked a little like this. Bree-hee-hee! Come further up, come further in!”
The limb on which Lewis climbed isn’t doctrinal, as no one knows what Heaven will really be like. But as conjecture goes, his Narnian vision was pretty fair, and certainly appealing.
I can’t confirm Lord Digory’s Platonic reference, but I think his statement was right on. Where many people imagine Heaven as some ethereal existence devoid of material beauty or pleasures, Digory’s vision gives it substance. Our dream worlds seem quite real to us while we’re dreaming, because our critical thought belongs to the conscious mind. Our dreaming minds usually accept anything they produce as real.
On a different level, our conscious minds accept anything they perceive as real, and declare the dim memories of dreams as surreal or symbolic. Lewis advanced that concept one level, declaring all we experience in this temporal existence to be just types and shadows of what God has prepared for us in Heaven, the real world.
I can hardly wait to venture “farther up, and farther in,” with my Lord Jesus.