It is clear that in this novel, Egdon Heath in some ways is presented as being more of a character than some of the characters themselves. Note the time and space that is devoted to describing Egdon Heath to us at the beginning of the novel before we even meet any characters at all. In addition, not only is Edgon Heath presented as something of a character itself, but it is also a powerful force in the novel that impacts the actions and thoughts of other characters. Consider the following description of Eustacia Vye and her relations with the Heath:
But celestial imperiousness, love, wrath, and fervour had proven to be somewhat thrown away on netherward Egdon. Her power was limited, and the consciousness of this limitation had biassed her development. Egdon was her Hades.
Note the way that the language used presents Eustacia Vye as being almost a celestial character as Egdon Heath is depicted as dragging Eustacia Vye down into her own personal hell.
For another example, consider the way that the Heath impacts the character of Clym in this following quote:
As he watched the dead flat of the scenery overpowered him, though he was fully alive to the beauty of that untarnished early summer green... There was something in its oppressive horizontality which too much reminded him of the arena of life; it gave him a sense of bare equality with, and no superiority to, a single living thing under the sun.
Note the overwhelming impression of the flatness and emptiness of the landscape, and how this becomes an oppressive force on Clym. Note the "sense of bare equality with, and no superiority to, a single living thing under the sun." The flatness of the Heath teaches Clym that he is equal to everybody else on earth and that any sense of superiority is but an illusion.