Quote by Arthur Schopenhauer

“Immediate reality is conditional upon individual consciousness. Thus the individual real existence of man also lies first and foremost in his consciousness. But this is as such necessarily ideational, and thus conditioned by the intellect and by the sphere and substance of the intellect's activity. The degree of clarity of consciousness, and consequently of thought, can therefore be regarded as the degree of reality of existence. But this degree of thought, or of clear consciousness of ones own existence and that of others, varies very greatly within the human race itself according to the measure of natural intellectual power, the extent to which this is developed, and the amount of leisure available for reflection. - On Psychology”

Quote by Arthur Schopenhauer