whether the same star will always give the same effect. But no one doubts the doctrine because it falls within the reigning scientific scheme. The importance of the scheme is illustrated by imagining some occurrence which does not fall within any scheme. You go to a strange foreign country, and among your first observations on your first day is that of a man standing on his head. If you are cautious, you will refrain from generalizing on the propensity of the inhabitants to stand on their heads; also half your friends will disbelieve you when you mention the incident. Yet your direct evidence is comparable to that respecting the shift of the spectral lines.
The production of a scheme is a major effort of the speculative Reason. It involves imagination far outrunning the direct observations. The interwoven group of categoreal notions which constitute the scheme allow of derivative extension by the constructive power of deductive logic. Throughout the whole range of these propositions respecting the interrelations of the forms of things, some of them allow of direct comparison with experience. In this way, the scheme as a whole has contact with experience. The extent of its conformity or non-conformity with observed fact can thus be explored. A scheme which, for a time at least, is useless methodologically, is one which fails to yield these observable contacts with fact.
An abstract scheme which is merely developed by the abstract methodology of logic, and which fails
