If you are a believer, expect powerful angels to accompany you in your life experiences. They appear and reappear. They are emotional creatures. While angels may become visible by choice, our eyes are not constructed to see them ordinarily any more than we can see the dimensions of a nuclear field, the structure of atoms, or the electricity that flows through copper wiring. Bats possess a phenomenally sensitive built-in radar system.
Some animals can see things in the dark that escape our attention.
Swallows and geese possess sophisticated guidance systems that appear to border on the supernatural. In his book, Though I Walk Through the Valley , Dr. Vance Havner tells of an old preacher who worked into the night on a sermon for his small congregation. His wife inquired why he spent so much time on a message that he would give to so few. It is no mere accident that angels are usually invisible. Though God in His infinite wisdom does not, as a rule, permit angels to take on physical dimensions, people tend to venerate them in a fashion that borders on worship.