Simplify the following text for a Grade 9 native English-speaking person.
Original: His novels also put forward a mystical philosophy that Rucker has summarized in an essay titled , with only a bit of irony , `` The Central Teachings of Mysticism '' ( included in Seek !
Simplified: His novels also show a mystical philosophy . Rucker explained this philosophy in an essay called The Central Teachings of Mysticism .