Thirty-Three Heavens, Doushuai Temple.
Aside from Hong Jun, the Daoist Ancestor, among the six great Saints, the strongest is the Hierarch of the Human Sect, Laozi, known as Daode Tianzun, with The Three Pure Ones deferring to him as their leader.
There's a widely spread anecdote about Laozi becoming a Saint.
Before Laozi had attained his Dao, he happened upon farmland one day and on a whim asked a farmer a question.
Laozi said, "How high is the sky, how wide is the earth?"
The farmer replied, "Nine zhang for the sky, five mu for the earth."
Laozi wondered with amazement, "The vast sky and earth, could they truly be of such a size?"
The farmer chuckled heartily, "When I look up, there's the nine zhang sky; when I bow my head, that's the five mu of arable land. This is my heaven and earth."
Laozi was astonished and suddenly saw the light, paying the farmer three deep bows in appreciation.