Our only difficulty here is that the mind flies away from the logical interpretation of sense datum to a ready-made notion of it brought over from abstract psychological inquiry. The belief in isolated sensory quales which are somehow forced upon us, and forced upon us at large, and thus conditioning thought wholly _ab extra_, instead of determining it as instrumentalities or elements selected from experienced things for that very purpose, is too fixed. Sensory qualities _are_ forced upon us, but _not_ at large. The sensory data of experience always come _in a context_; they always appear as variations in a continuum. Even the thunder which breaks in upon me (to take the extreme of apparent discontinuity and irrelevancy) disturbs me because it is taken as thunder: as a part of the same space-world as that in which my chair and room and house are located; and it is taken as an influence which interrupts and disturbs, _because_ it is part of a common world of causes and effects. The solution of continuity is itself practical or teleological, and thus presupposes and affects continuity of purpose, occupations, and means in a life-process. It is not metaphysics, it is biology which enforces the idea that actual sensation is not only determined as an event in a world of events,[26] but is an occurrence occurring at a certain period in the control and use of stimuli.[27] 2. _Forms of thinking data._--As sensory datum is material set for work of thought, so the ideational forms with which thought does its work are apt and prompt to meet the needs of the material. The "accessory"[28] notion of ground of coherence turns out, in truth, not to be a formal, or external, addition to the data, but a requalification of them. Thought is accessory as accomplice, not as addendum. "Thought" is to eliminate mere coincidence, and to assert grounded coherence. Lotze makes it clear that he does not at bottom conceive of "thought" as an activity "in itself" imposing a form of coherence; but that the organizing work of "thought" is only the progressive realization of an inherent unity, or system, in the material experienced. The specific modes in which thought brings its "accessory" power to bear--names, conception, judgment, and inference--are successive stages in the adequate organization of the matter which comes to us first as data; they are successive stages of the effort to overcome the original defects of the data. Conception starts from the universal (the common element) of sense. Yet (and this is the significant point) it does not simply abstract this common element, and consciously generalize it over against its own differences. Such a "universal" is _not_ coherence just because it does not _include_ and dominate the temporal and local heterogeneity. The _true_ concept (see I, 38) is a system of attributes, held together on the basis of some ground, or determining, dominating principle--a ground which so controls all its own instances as to make