Two different aspects of knowledge are frequently distinguished by the logician and philosopher: the non-repetitive and the repetitive. However, this distinction is imperfectly supported by careful observation, since no two objects or events are known to be exactly alike, and no two objects or events are completely different. In spite of this relativisitic state of affairs, there is some value in distinguishing between the thinker or student who is primarily interested in the unique, peculiar and non-repetitive phenomena of experience and the person whose emphasis is on general, repetitive and predictable observations. The approaches and mental operations of these two classes of agents are essentially different, although the world they experience may be the same. The first concentrates on one item at a time, the result being a restriction of his attention away from other objects or events of the same class. The generalizing student usually controls his mental operations fully as much, but in this case attention to the unique is held in abeyance and comparisons are deliberately fostered. The essential difference thus becomes a matter of the rejection of the comparative method of procedure by the first and overwhelming dependence on that method on the part of the generalizer.