1 Corinthians 15.35-50

Paul is being challenged about the nature of the resurrection body. What's it actually like? At one level Paul's argument seems very straightforward. He seems to be saying that we are very used to categorising the natural world around us. We categorise what we see according to the different properties things have - different 'glories' even. The stars are classified, different sort of animals and plants are categorised. Each is different and we are very used to diversity of the world around us. The spiritual and the physical are additional categories. Both with their own properties - 'glories'.
This argument works very well for those who have accepted that a new creation has taken place - that there is a 'spiritual man' who has been experienced. The logic is sound - there is now a new human being that is connected to the current human being in the same way that a seed is is connected to the plant. First the physical is sown and through growth and maturity becomes the spiritual man. The physical is the precursor to the spiritual, a necessary part of the cycle of growth. As a seed becomes a plant, as a chrysalis becomes a butterfly so physical man becomes spiritual man. This is a perfectly rational way of processing the additional experience of Christ.
Of course, it doesn't help people accept that there is a resurrected spiritual phase of humanity. But then the question of what the spiritual body will be like cannot be asked unless the possibility of a resurrected body existing at all has been considered.
Once our world view has accommodated the greater reality we have now experienced after the resurrection of Christ, we can then begin to explore the nature of that broadened awareness. After all, it is only once you have accepted that the world is round that you will venture to new shores to see what's there!