Speaking from this point of view, the decisive consideration as between instrumentalism and analytic realism is whether the operation of experimentation is or is not necessary to knowledge. The instrumental theory holds that it is; analytic realism holds that even though it were essential in _getting_ knowledge (or in learning), it has nothing to do with knowledge itself, and hence nothing to do with the known object: that it makes a change only in the knower, not in what is to be known. And for precisely the same reason, instrumentalism holds that an object as a knowledge-object is never a whole; that it is surrounded with and inclosed by things which are quite other than objects of knowledge, so that knowledge cannot be understood in isolation or when taken as mere beholding or grasping of objects. That is to say, while it is making the sick man better or worse (or leaving him just the same) which determines the knowledge-value of certain findings of fact and certain conceptions as to mode of treatment (so that by the treatment they become definitely knowledge-objects), yet improvement or deterioration of the patient is other than an object of cognitive apprehension. Its knowledge-object phase is a selection in reference to prior reflections. So the laboratory experiment of a chemist which brings to a head a long reflective inquiry and settles the intellectual status of its findings and theorizings (thereby making them into cognitive concerns or terms and propositions) is itself much more than a knowledge of terms and propositions, and only by virtue of this surplusage is it even contemplative knowledge. He knows, say, tin, when he has made tin into an outcome of his investigating procedures, but tin is much more than a term of knowledge. Putting the matter in a slightly different way, logical (as distinct from naïve) realism confuses means of knowledge with objects of knowledge. The means are twofold: they are (_a_) the data of a particular inquiry so far as they are significant because of prior experimental inquiries; and (_b_) they are the meanings which have been settled in consequence of prior intellectual undertakings: on the one hand, particular things or qualities as signs; on the other, general meanings as possibilities of what is signified by given data. Our physician has in advance a technique for telling that certain particular traits, if he finds them, are symptoms, signs; and he has a store of diseases and remedies in mind which may possibly be meant in any given case. From prior reflective experiments he has learned to look for temperature, for rate of heartbeats, for sore spots in certain places; to take specimens of blood, sputum, of membrane, and subject them to cultures, microscopic examination, etc. He has acquired certain habits, in other words, in virtue of which certain physical qualities and events are more than physical, in virtue of which they are signs or indications of something else.