For both men, Beauty was connected to the eternal. Socrates, being at least somewhat (and perhaps completely) atheistic, does not immediately or necessarily connect the concept of the eternal with the concept of the divine, however, but rather recognizes the inherent Beauty in the only act of immortality that mortals can engage in -- procreation and generation, which leads to "beauty in birth." The physical act of love between a man and a woman is described by Socrates -- through the voice of Diotima -- as an act of supreme beauty, and its effects are equally beautiful, as it causes immortality and hence touches upon the eternal. Beauty is also connected to love because love cannot occur with deformity; the closer a material thing comes to representing its ideal form, the more Beautiful it becomes because it is closer to touching the eternal. This argument in some ways celebrates material beauty, though only insofar as it connects to eternal Beauty. Plotinus sees this connection also, but departs from Socrates in his recommendation to any capable man to "let him arise and withdraw into himself, foregoing all that is known by the eyes, turning away for ever from the material beauty that once made his joy...he must know them for copies, vestiges, shadows, and hasten away towards That they tell of." Plotinus believes that true Virtue -- which is itself Beautiful -- is best attained not by recognizing the presence of the Divine in material beauty, but by turning away from these imperfect representations.

Plotinus carries this argument to its logical extremes, insisting that the Soul must be made Beautiful (by becoming...

At this point, his mysticism has largely taken over, and his departure from Socrates is nearly complete. This does not represent a disagreement with Socrates regarding the recognition and nature of Beauty however, but rather shows Plotinus' willingness to extend the effects of his thoughts and beliefs to extremes that Socrates did not approach. For Plotinus, philosophy was a tool for creating a system of proper human behavior, and he uses his treatise on Beauty as a tool to preach to others to become virtuous; for him, the realities of the mortal world cannot be separated from the eternal.
Socrates shares elements of these beliefs in the purpose of philosophy, but his goal is more the pursuit of objective and logical truth. He is far less concerned with defining correct behavior and urging other men to follow it; rather, his dialogues and basic philosophy shows that he is consumed with the open and honest pursuit of logic and truth; he encourages other men to think clearly and openly about how they act, but does not try to persuade them to act in certain ways.

The difference of purpose forms the major difference between Socrates' thoughts on Beauty in his Symposium and Plotinus' own ideas on the subject in his Ennead. On the actual points of the philosophies -- disregarding the ideas and attitudes towards their applications -- the two men are very much in agreement. The Ideal Beauty is that which is eternal, and which the Soul responds to in a way of kinship and excitement. Recognizing it is as simple as allowing it to be.