Only in very extreme cases, however, does the assured, unquestioned element reduce to as low terms as we have here imagined. Certain things come to stand forth as facts, no matter what else may be doubted. There are certain _apparent_ diurnal changes of the sun; there is a certain annual course or track. There are certain nocturnal changes in the planets, and certain seasonal rhythmic paths. The significance of these may be doubted: Do they _mean_ real change in the sun or in the earth? But change, and change of a certain definite and numerically determinate character is there. It is clear that such out-standing facts (ex-istences) constitute the data, the given or presented, of the thought-function. It is obvious that this is only one correspondent, or status, in the total situation. With the consciousness of _this_ as certain, as given to be reckoned with, goes the consciousness of uncertainty as to _what it means_--of how it is to be understood or interpreted. The facts _qua_ presentation or existences are sure; _qua_ meaning (position and relationship in an experience yet to be secured) they are doubtful. Yet doubt does not preclude memory or anticipation. Indeed, it is possible only through them. The memory of past experience makes sun-revolving-about-earth an object of attentive regard. The recollection of certain other experiences suggests the idea of earth-rotating-daily-on-axis and revolving-annually-about-sun. These contents are as much present as is the observation of change, but as respects worth, they are only possibilities. Accordingly, they are categorized or disposed of as just ideas, meanings, thoughts, ways of conceiving, comprehending, interpreting facts.