The tendency of such speculations as these towards universal Skepticism, or even absolute Nihilism, with the exception only of certain fleeting phenomena of Consciousness, is too apparent to require any formal proof; and it must be equally evident that they contradict some of the most universal and deeply-rooted convictions of the human mind. The ultimate ground of every system of Idealism which excludes the knowledge of an external world must be one or other of these two assumptions, or a combination of both: either, that our knowledge cannot extend beyond the range of consciousness, which takes cognizance only of ideas, or of subjective mental states; or that any attempt to extend it beyond these limits, so as to embrace external objects as really existing, can only be successful on this condition,--that we _prove_, by reasoning from the subjective to the objective, that there is a necessary _logical_ connection between the state of the one and the reality of the other. Each of these assumptions is equally groundless. It is true that consciousness, strictly so called, takes cognizance only of what passes within; it is not true that consciousness, in this restricted sense, is commensurate with our entire knowledge. It is true that we acquire our knowledge only through the exercise of our mental faculties; it is not true that our mental faculties are the only sources of our knowledge, nor even that, without the concurrence of certain objects, they could give us any knowledge at all. It is true that there must be a connection between the subjective and the objective; it is not true that this connection must be established by _reasoning_, or that we must _prove_ the existence of an external world distinct from the thinking mind, before we are entitled to believe in it. For a great part of our knowledge is _presentative_, and we directly perceive the objects of Nature not less than the phenomena of Consciousness.