It is "Vaguely Remembered", which is the title poem of a painting by Feng Zikai.
The original text is: I saw my son feeding him through the window. I recalled that when I fed my son, "Feed my son to make me hungry, feed your son to make me hungry." It means seeing myself through the window. When my son feeds his child, he reminds me of the time when I fed my child. Now that my child is starving me, his child will starve my son in the future. It means that a person should be filial to his elders, otherwise he will get retribution.