  Perhaps the most obvious objection to idealism is that it makes real things no different from imaginary ones—both seem fleeting figments of our own minds, rather than the solid objects of the materialists. Berkeley replies that the distinction between real things and chimeras retains its full force on his view. One way of making the distinction is suggested by his argument for the existence of God, examined above: Ideas which depend on our own finite human wills are not (constituents of) real things. Not being voluntary is thus a necessary condition for being a real thing, but it is clearly not sufficient, since hallucinations and dreams do not depend on our wills, but are nevertheless not real. Berkeley notes that the ideas that constitute real things exhibit a steadiness, vivacity, and distinctness that chimerical ideas do not. The most crucial feature that he points to, however, is order.  The ideas imprinted by the author of nature as part of rerum natura occur in regular patterns, according to the laws of nature (“the set rules or established methods, wherein the mind we depend on excites in us the ideas of sense, are called the Laws of Nature” PHK 30). They are thus regular and coherent, that is, they constitute a coherent real world.