Clive Staples Lewis. Just Christianity (№ 396219)

Whether it is necessary to pay attention to people who are trying to make the Christian hope of "heaven" when they say,
what they do not want to spend eternity playing the harp. These men I answer, that if they cannot understand books written for adults, you should not talk about them.
All the images in Scripture (harps, crowns, gold) is simply an attempt to Express the inexpressible. Musical instruments are mentioned in the Bible because to many people (not all) music best conveys vostorgina and a sense of infinity. The crowns say that those who are United with God in eternity share His splendour and power and joy. Gold symbolizes timelessness (because it does not rust) and enduring value. People who understand all of these characters literally, with the same success could have thought that, advising us to be as doves, Christ wanted us to be carrying eggs.