Impressed by a screen painting in the home, Gennai summoned the artist named Naotake and said to him, 'Try to paint the rice cake offering as if looking at it from above,' and when Naotake painted only a double circle, Gennai exclaimed, 'I cannot tell if that is the tray or the rice cake,' and immediately taught him a method of painting with shadows.
その際、宿の屏風絵に感心した源内がその絵の作者だという直武を呼び、「供物餅を上から描いてみなさい」と直武に描かせてみせたところ、二重丸を描いた直武に「それではお盆なのか餅なのか分からない」と言い、即座に陰影法を教えたという。