Only in very extreme cases, however, does the assured, unquestioned element reduce to terms as low 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, in the thought-function. _b_) 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, that is, of its reference and connection. The facts qua presentations or existences are sure; _qua_ meanings (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 connection they are only possibilities. Accordingly, they are categorized or disposed of as ideas, meanings, thoughts, ways of conceiving, comprehending, interpreting facts. Correspondence of reference here is as obvious as correlation of existence. In the logical process, the datum is not just external existence, and the idea mere psychical existence. Both are modes of existence--one of _given_ existence, the other of _possible_, of inferred existence. And if the latter is regarded, from the standpoint of the unified experience aimed at, as having only _possible_ existence, the datum also is regarded as incomplete and unassured. Or, as we commonly put it, while the ideas are impressions, suggestions, guesses, theories, estimates, etc., facts are crude, raw, unorganized, brute. They lack relationship, that is, assured place; they are deficient as to continuity. Mere change of relative position of sun, which is absolutely unquestioned as datum, is a sheer abstraction from the standpoint either of the organized experience left behind, or of the reorganized experience which is the end--the objective. It is impossible as a persistent object. In other words, datum and ideatum are divisions of labor, co-operative instrumentalities, for economical dealing with the problem of the maintenance of the integrity of experience.