compelling argument that primary and
             secondary qualities are, together, one thing. As the materialist
             believes, primary qualities of an object are those things that are
             abstract (not sense oriented). Examples of these would be number,
             figure, motion, and extension. Secondary qualities are those things
             that are concrete (sense oriented), such as color, smell, sound, and
             taste. The materialist feels that these primary qualities persist even
             when the secondary ones are not there. Thus, if a person were blind,
             then that individual would not be able to hear or to touch items; yet
             the so-called real qualities such as figure would remain existent in
             the objects. As previously shown, the materialist is agnostic in his
             belief of these real (primary) qualities. It is here that Berkeley
             directs an alternate hypothesis: that the abstract primary qualities
             don't exist at all. In fact, the immaterialist position states that
             these qualities are merely secondary in nature, as they, too, can not
             be perceived as being separate from an object. For instance, if a
             person is asked to imagine a primary quality alone, as an abstraction,
             it is impossible. To illustrate this point, suppose that a person is
             asked to think simply of number alone. This person may reply that the
             idea he is formulating is that of three red spheres. In truth this is
             not an abstract idea, because when the qualities of color (red) and
             shape (sphere) are taken away, all that is left is three of nothing!
             Thus, it is impossible to think of the abstraction of number, given
             that an abstract quality can not focus on anything concrete (such as
             ...