Open Society - Guidelines of the Heart by Ryuho Okawa 234 -

The spiritual world is extremely large, and its size cannot be measured. No one knows how vast it is. It is so vast that it cannot be measured at all. Within that, there is a part that relates to the three-dimensional world, a magnetic field related to matter, where humans reside.
(From Chapter 2 'The Principle of Possession')

Humans are born from the spiritual world, which is the original world, inhabit physical bodies, and live within the material world. And, in a sense, we are being tested on 'how much of a spiritual view of life we can acquire while living in this material world (omitted)'.
(From Chapter 2 'About the Afterlife')