That races living inland must long have remained ignorant of the daily and monthly sequences of the tides, and that intertropical races could not early have comprehended the phenomena of northern winters, are extreme illustrations of the influence which relative frequency has on the recognition of uniformities. Animals which, where they are indigenous, call forth no surprise by their structure or habits, because these are so familiar, when taken to a part of the earth where they have never been seen, are looked at with an astonishment approaching to awe—are even thought supernatural: a fact which will suggest numerous others that show how the localization of phenomena, in part controls the order in which they are reduced to law. Not only however does their localization in space affect the progression, but also their localization in time. Facts which are rarely if ever manifested during one era, are rendered very frequent in another, simply through the changes wrought by civilization. The lever, of which the properties are illustrated in the use of sticks and weapons, is vaguely understood by every savage—on applying it in a certain way he rightly anticipates certain effects; but the action of the equally simple wedge, which is not commonly displayed till tool-making has made some progress, is less early generalized; while the wheel and axle, pulley, and screw, cannot have their powers either empirically or rationally known till the advance of the arts has more or less familiarized them. Through those various means of exploration which we have inherited and are ever increasing, we have become acquainted with a vast range of chemical relations that were relatively non-existent to the primitive man: to highly developed industries we owe both the substances and the apparatus that have disclosed to us countless uniformities which our ancestors had no opportunity of seeing, and therefore could not recognize. These and sundry like instances that will occur to the reader, show that the accumulated materials, and processes, and appliances, and products, which characterize the environments of complex societies, greatly increase the accessibility of various classes of relations; and by so multiplying the experiences of them, or making them relatively frequent, facilitate their generalization. To which add, that various classes of phenomena presented by society itself, as for instance those which political economy formulates, become relatively frequent and therefore recognizable in advanced social states; while in less advanced ones they are too rarely displayed to have their relations perceived, or, as in the least advanced ones, are not displayed at all.