In the view of realists, individual things interact by physical connection and the relations among things are mediated by physical processes that connect them to human brains and give humans a determinate chain of action to them and correct knowledge of them. Kant was aware of problems with the positions of both of these thinkers. He had been influenced by the physics of Newton and understood that there is a physical chain of interactions between things perceived and the one who perceives them. However, an important function of mind is to structure incoming data and to process it in ways that make it other than a simple mapping of outside data. The salient element here is that space and time, rather than being real "things-in-themselves" or empirically mediated appearances (), are the very forms of intuition () by which we must perceive objects. They are hence neither to be considered properties that we may attribute to objects in perceiving them, nor substantial entities of themselves. They are in that sense subjective, yet necessary, preconditions of any given object insofar as this object is an appearance and not a "thing-in-itself". Humans necessarily perceive objects as located in space and in time. This condition of experience is part of what it means for a human to cognize an object, to perceive and understand it as something both spatial and temporal: "By "transcendental idealism" I mean the doctrine that appearances are to be regarded as being, one and all, representations only, not things in themselves, and that time and space are therefore only sensible forms of our intuition…" Kant argues for these several claims in the section of the "Critique of Pure Reason" entitled the "Transcendental Aesthetic". That section is devoted to inquiry into the "a priori" conditions of human sensibility, i.e. the faculty by which humans intuit objects. The following section, the "Transcendental Logic", concerns itself with the manner in which objects are thought. Xenophanes of Colophon in 530 BC anticipated Kant's epistemology in his reflections on certainty. "And as for certain truth, no man has seen it, nor will there ever be a man who knows about the gods and about all the things I mention. For if he succeeds to the full in saying what is completely true, he himself is nevertheless unaware of it; and Opinion (seeming) is fixed by fate upon all things." Certain interpretations of some of the medieval Buddhists of India, such as Dharmakirti, may reveal them to be transcendental idealists, since they seemed to hold the position of mereological nihilism but transcendental idealists who held that their minds were distinct from the atoms.