Some Creationists argue:
The full Darwin quote in fact gives a prescription for how organs of great complexity can arise by slow degrees. A suitable sequence of events has been found, and there are numerous sea creatures alive today whose eyes are stages in that sequence.
It has been calculated that a complete fish eye could have evolved in less than 350,000 years, with almost no mutations. Something that easy should have happened many times, and in fact, taxonomists think that eyes have evolved more than 40 times.
Scientists consider their explanation of eye evolution to be a great triumph for Darwin's idea of Natural Selection.