The eyes cannot see without varying the perception. Thought dwells over rapid, constant change. There is no moment in which any power of the soul remains the same; senses and faculties in their nature instinctively stimulate the alteration of the state. No simplicity at any given time, nor identity at different times. Distinct scenes make their appearance, pass and repass, slip and mix with an infinite variety of attitudes and situations: the mind opens the curtain, becoming theatre.