Take the first stairway on the left down to the lower floor of the Lehman Gallery. Once at the bottom of the stairs, walk to the opposite side of the exhibition space, where you’ll see a row mostly portraits. Many sombre men in dark, 17th-century Dutch clothing will be looking back at you. At the far end, to your left, you’ll see Rembrandt’s Self Portrait from 1660, painted when he was 54.