In A Wizard of Earthsea, there's no real separation between man and the natural world. Even though there's magic and all sorts of other supernatural things, everything is part of one natural system. For instance, magic is great and all, but you still need to eat regular food, as Ged explains to Vetch's sister (9.60). That's one serious aspect of man and the natural world: man, even a magician, is part of the bigger world too, and is subject to many of its rules. Also, a big part of Ged's learning (he's a wizard-in-training) is his place in the natural world. He learns that man should not upset the natural balance. Wizards could do the most damage to the balance, so they have to be the most careful when they're dealing with the natural world.