“Every sides of the cube were keys, but only one door leads beyond them.”

“A locked big door always kneels down in front of its little key! Every giant has a weak side!”

“be careful... beyond the door lies a completely different world... but don't be afraid.... and don't stop... cause only your heart knows where your journey will lead you....”

“A brick could be used as a key to unlock a door disguised as a brick wall. The security in the lock lies not with a one-of-a-kind key, but with a key that looks like hundreds of other potential keys that make up the door.
”

“The best rooms were all on the left-hand side (going in), for these were the only ones to have windows, deep-set round windows looking over his garden and meadows beyond, sloping down to the river.”

“...salvation is not something that happens only at the end of a person's life. Salvation happens every time someone with a key uses it to open a door he could lock instead.”