D&C 131: 7 There is no such thing as immaterial matter. All ^aspirit is matter, but it is more fine or pure, and can only be discerned by^bpurer eyes;

 8 We cannot ^asee it; but when our bodies are purified we shall see that it is all ^bmatter.

As spirit is more fine or pure we must develop our finer senses to perceive it.  Developing this capacity through obedience to commandments and Christ-like service is both a blessing and valuable skill in missionary work.