Whereas we have spoken so far (especially in chapter I) quite plainly of the world of our experiences as of the "real" world, we must now say something about a manner of speaking that uses "real" and "experience" as designating a pair of opposites. The difference between the terms "real" and "apparent" plays a great role in ordinary life as well as in natural science. For example we say: "apparently" the detective took a quiet walk, but "really" he carefully watched the entrance to a jeweller's shop. Or: The stone on which I stepped was "apparently" quite fast, but it was "really" so loose that it broke off.