I believe that the first step in the setting of a real external world is the formation of the concept of bodily objects and of bodily objects of various kinds.
Albert EinsteinConsider the concepts referred to in the words 'where', 'when', 'why', 'being', to the elucidation of which innumerable volumes of philosophy have been devoted. We fare no better in our speculations than a fish which should strive to become clear as to what is water.
Albert EinsteinMay the conscience and the common sense of the peoples be awakened, so that we may reach a new stage in the life of nations, where people will look back on war as an incomprehensible aberration of their forefathers!
Albert Einstein