Arvoitus

How quickly can you find what is so unusual about this paragraph? It looks so ordinary that you would think nothing was wrong with it at all, and in fact, nothing is. But it is unusual. Why? If you study it, and think about it, you may find out, but I am not going to assist you in any way... you must do it without coaching. No doubt, if you work on it, it will dawn on you... who knows? Go to work now and try your skill. Par is about half an hour.
Kuka arvaa?