Ouyang Xiu's 6 1 layman, so what does this "6 1" mean? Can you explain it in detail?

There are these two sentences in Ouyang Xiu's Biography of the Six-Day Layman:

"My family has a collection of 10,000 books, including 1,000 copies of epigraphy. Since three generations, I have always kept a pot of wine." ,

"For me, an old man is older than these five things, isn't it June 1st? 』

Someone asked Ouyang Xiu what "June 1st" was. He said: "My family has 10,000 books, including 1,000 epigraphy left over by three generations, a piano, a chess game and a pot of wine." There are only five one-dollar bills? "He said," and I, an old man, was mixed in one of these five schools. Isn't it' June 1'? "

This is the origin of his self-proclaimed "six-year-old layman"