Experiencing is one of the major factors of expertise. One can only obtain the knowledge of phenomena in the real world through accumulating experiences. To learn theories and definitions of concepts may provide basic knowledge for the specific matters concerned. But more essential is such real knowledge which, in a sense, means the adaptation. Here the accumulation of experience is described in terms of the concepts of an experience sequence and a filter base. Forming an experience sequence is, at the same time, the process of inductive concept formation. These ideas are utilized for the reasoning process at the man-machine interface.