Parmenides' poem starts with a prologue in which he is transported beyond the gates of day and night in a chariot drawn by immortal horses steered by the daughters of the sun. As Heidegger puts it, "far beyond the usual abidence of man" he is greeted by a goddess who reveals to him the truth.
She tells him there are only two ways that can be thought: either being is, or being is not. She then warns against the path of not being. How can you say that nothing is? That way leads only to paradox and confusion. The other, and correct path, is that being is. She then defines some of these properties. Being is one, because how could it be differentiated from itself. Being is whole. It has no beginning and no end. Time is an illusion. This is the gist, though the meat is in the details which I will talk about in later posts.
The final, and probably longest part, of the poem was a discussion of the common understanding of nature with its comings and goings. There is not much of this section left. But in the existing fragments he discusses the fiery essence of the universe, it's various realms, and even how progeny inherit from their parents.
Many have noted the contradictions between the elements. The prologue involves movement and a normal sense of time. How is that possible given the changeless nature of being? And why do the third part in which the goddess imparts the common understanding of those who do not understand the true nature of being? If being I some and unchanging how can the discussion, or anything for that matter, progress or change?
I think it is actually possible to reconcile these contradictions, and actually find something of more than academic value here.