Diotima initially describes Eros as a daemon. He is described as an intermediary between the divine (immortal) and the mortal plane. He is the son of Penia (Poverty) and Poros (Resource). He is always poor, and in need of something. He is interested in capturing the beautiful and the good. Among his attributes that we can recognize later of importance are him being: courageous (since he could not proceed on the ladder of love without courage), philosophizing through all his life (again, we can see this happening when the lover is guided properly on how to love), between wisdom and lack of understanding (thus having a desire to philosophize). This Eros, the daemon, is a description, an image of the lover.
At 205 D, under my interpretation, Diotima changes from discussing the lover (Eros) to discussing the love that the lover has (eros) for the beautiful and the good. Here we are offered two definitions for eros.
One is a general definition that applies to most humans: “In brief, eros is the whole desire of good things and of being happy,” (205 D). People approach this in many different ways, like “money-making, love of gymnastics, or philosophy” (205 D). But we do not call them lovers, unless they apply themselves earnestly to a single one. We can see this happening for example in the ninth book of The Republic, where depending on which part rules a person’s soul, if it has a clear dominion over him and makes him earnestly apply himself to the interests of that part of the soul, we call him a lover of wisdom, lover of honor, or lover of money.
The second definition is at 206 E: “eros is of the good’s being one’s own always”. This seems to be a lot more abstract than the love most people have in day to day life. People have an eros for another person, or they have an eros for an object or an activity in general – but for the good itself? In my first Symposium essay, I argued in detail that this definition is compatible with the first one, and it follows logically from it if one has a philosophically predisposed soul (with a calculating part minding its own business, and wise enough, to ask questions and follow through with their logic).
A person wants good things and to be happy. But what exactly are good things? What makes a thing good? What is this attribute of goodness that good things partake in? What is the good? If a person wants to have good things, then he must be in possession of knowledge of the good. But is this knowledge something that can be obtained once, and then discarded? No. It must stay with the person always, so that he may continuously and constantly distinguish what these good things are. Thus one wants to own the good, always.
Another distinct approach to understanding how one can arrive at this second, more particular, definition of eros, is that since eros actually is caused by the desire for immortality, and the best way to satisfy it is to give birth to true virtue, in addition of beauty itself, a person must also have knowledge of the good itself. For how can a person know truly “what sort the good man must be and what he must practice” (virtue, 209 C), without knowing what the good itself is?