To a creature with a zero-dimensional consciousness, the world consists of nothing but the one point of which it is conscious. Anything that enters that point seemingly comes out of nowhere, and when it leaves it seems to cease to exist. If such a creature were to move along the surface of, say, a leaf, it would become conscious of one point after another on the leaf. The points it had left would, for it, be the future. But we, with our ability to view the whole leaf, could see both the past and the future of the zero- dimensional creature at a glance.
Nothing exists for it except what lies along the line of which it is conscious.
If anything enters this line, it appears to come into existence to the one-dimensional creature. If anything leaves this line, it appears to go out of existence. If such a creature moves its line of view, say, by turning its head, it will see in a number of directions in succession. Such a creature conceives only a plane of existence. If it views a house and sees someone open the door of the house and come out, to its consciousness that person appeared out of nowhere.