This is the nature of the philosopher; a person who seeks knowledge and truth; the "good," with his whole being. This search sets him apart from the rest of humanity, and also enables him to lead them where necessary. Socrates emphasizes that it is often dangerous to try and force people to emerge from the cave, as a sudden emergence could have the above-mentioned effect of turning these people away from the sun forever. The divided line image from Book VI of the Republic is a rather complicated preliminary image to the Allegory of the Cave in the following Book. Here Socrates explains the division between the physical and intellectual worlds by means of a line that is divided into two. One of the lines is below the other and represents the physical, or visible world. The other line, above the first, represents the mental, or the intellectual world. This line is further divided into two, and again one above the other. Here it is also possible to become so convinced of the truth of the "lower" intellect that there is no further search for any higher "good." Socrates warns that this halts the philosopher on his way to the ultimate truth. The lower half of this line is then "reason," which is occasionally required to accept without question, and "intelligence," which understands the ultimate good by questioning all existing knowledge. This is the goal of the true philosopher. In his role as leader, he is to search until he finds this final level of the intellectual and thereby attains the highest good.

In the Nicomachean Ethics, Aristotle criticizes the...

The reason for this is the fact that all human life is integrated with the world around it. Nothing, not even the good, can exist separately from their points of reference. Intelligence and sight for example are enjoyed as good because they enhance the human experience of areas of knowledge and physical beauty that can be seen. Aristotle then argues that, to call something good simply to relate to the Idea of good, would make that very idea empty, because it is meaningless.
The good can then also not refer to only a single form. Aristotle points out that different things are good for different people. They are good insofar as they are useful to the person beholding or using them. The doctor, for example, experiences his studies in healthcare as good, because they help him in his profession. Knowledge in carpentry would therefore be of little use to him. The good therefore is connecting with various ideas, rather than a single Form.

Sources

Aristotle. Nicomachean Ethics, trans. W.D. Ross. http://www.constitution.org/ari/ethic_00.htm

Hooker, Richard. "Greek Philosophy: Plato." 1996. http://www.wsu.edu/~dee/GREECE/PLATO.htm

Plato. The Republic, Book VI and VII. Copyright by Richard Hooker, 1996. http://www.wsu.edu/~dee/GREECE/ALLEGORY.HTM