The Philosophy of Evolution

ce is to reach this proposition, to discover and assert the principle of classification--in other words, to formulate metaphysically what nature has presented physically. We must find, then, the first or fundamental law of thinking in this integration or classification. This fundamental law may be subdivided into two species, according to the two terms of the proposition; of which the first may be stated thus: "Every possible object of thought is to a certain extent identical with every other"; and as the proposition implicitly states disagreement, the second may be stated thus: "Every possible object of thought is to a certain extent diverse from every other." The first gives the positive (subjective) condition of the proposition, the second the negative (objective) condition: both together constitute the conditions of thinking. The proposition is thus the assertion of the same in the different. The proposition also asserts, implicitly, the tertium quid, or the basis of classification--the