It meant that a person could survive solely on the energies provided by the Heaven and Earth, losing the need to eat the five grains. Such a survival method allowed a person’s body to be purer. With fewer impurities, they could also live longer.
The ancients held this state in high esteem, so there were plenty of documentation in the ancient books.
Of course, Yi Yun was still far from the state of avoiding grains. Yi Yun felt that even if he had reached the state where he could avoid grains, he felt that he would never succumb to that state.
On Earth, Yi Yun was a glutton, erm…that lacks sophistication. It should be said that Yi Yun was a food connoisseur – yes, a food connoisseur. The former was a symbol of laziness and gluttony, while the latter was for someone who could enjoy the beauties of life.