How can a person believe in unseen powers?

How can a person believe in unseen powers when he is absorbed and narrowed by the seen? by the essentials of that life?

I did not at all events, and I approached the close of life with a fear that was almost horror. I was not wicked, as the world thinks of wickedness, but bound by the material and visible, and when the final test came, I could not find the spiritual and unseen. So I passed, and my friends must have had little consolation in the thought of my entering upon new conditions.

I sank out of extreme pain into a sleep so gentle and peaceful, I think it would have been all right if I had never awakened again, but the waking came slowly, hardly consciously, until I finally knew that the terror was over, and about me were kindness and helpfulness. 

You probably cannot imagine those first moments of exquisite joy that I felt in the new life, a new opportunity to make good in a way, in a small way, but with such visions of larger opportunity before me that the life here [in the world of spirits] has become truly the great adventure.

—Spirit Unknown