After looking at 100 paintings of bottles, or bottles with flowers etc. I went to the bathroom and dried my hands on a grey paper towel. Immediately my perception of the colour of the paper towel had shifted. At first I thought they must have put grey paper towels in the bathroom because they speak so eloquently and knowingly to the paintings. But after I left the museum I kept finding other bathrooms with the same grey paper towels. So yes, it was my eyes. And Giorgio Morandi.