The scope of conceptual consciousness is much wider than that of perceptual; concepts bring a much wider range of reality to our awareness than percepts can.
Concepts are so powerful because, as AR was fond of putting it, they serve to ``reduce the units.'' This point is called the ``crow epistemology'' by Objectivists. The reference is to a psychological experiment some years ago. When two people went into the woods, the crows went into hiding and waited for both to come out-even if they come out one at a time. If three people went in, again the crows waited for all three. If five went in and four came out, however, the crows came out of hiding.
The point is that the number of individual units consciousness can attend to at a given instance is severely limited (I've heard numbers from 3 to 7 for humans). Thus concepts, by integrating an unlimited number of individual units into a new single unit, serve to greatly expand the range of consciousness. Consider the concept ``man.'' The referent of the concept ``man''-the objects that the word refers to-are all men: every man that ever was, is, or will be. This enormous sum is represented by a single unit, the word ``man.''
A related way concepts serve to increase the range of our consciousness is to condense our knowledge into convenient handles; that is, they serve as handy file-folders for the information we collect. Again, consider ``man.'' For both a ten year old child and a 60 year old physician, the concept ``man'' refers to the same objects: men. Consider how much more about men the physician knows, yet this knowledge is filed under that same concept. All that knowledge is condensed into a single unit, ready for instant access. Once a concept is formed, it is a repository used in our never-ending accumulation of further knowledge.