오로지 눈을 비롯한 감각기관을 사용하여 그 실재가 어떠한지 판명할 수 있다고 생각했으나 시간이 흐를수록 그것이 과연 실체인지 미술가 스스로가 확신할 수 없었다.
It was thought that only the eyes and other sensory organs could be used to determine what the reality was, but as time went on, the artist himself could not be sure that it was a reality.