My heart seems like a duck to water.

It refers to the things you have experienced, and you know the joys and sorrows. Just like "drinking water, knowing yourself when you are warm and cold". The source is Song He's "Book of History: Memories of Long Mian Hai".

"Yan Miaoli, with the heart in the sky, all samadhi, is an arhat, lay also. Take one of the laymen as an example, draw this arhat, and take one of the great minds as an example to get this arhat. When you know it, painting comes first. Painter, winner, bandit In the past, the boundless monk only inherited the memory of the Buddha, but it was not easy to draw this, and it was not easy to get this. As for Dharma, there is no way, no phase, such as fish drinking water, knowing oneself in cold and warm. It's also a record, built for painting. It was the 160 th day of the second year of Jubilee, and I was a beginner in Wang Mai. "